Sunday Sensational Science

Arizona Rockhounding

One thing Arizona doesn’t lack is rocks. We’ve got nearly every type of rock on earth, plus a big one from space. And they’re not buried under a bunch of inconvenient vegetation. They’re right out in plain sight. For the geologist, Arizona is utter paradise.

I did some rockhounding in my home state, and subjected you to the results in Arts & Cats I, II & III. You even got to see my horrible attempt at photographing the completed collection:

Now comes the science part, which is a hell of a lot more interesting than just looking at someone’s random collection of rocks. We’ll be discussing a select sampling, delving into deep time and discovering how little (well, mostly big) rocks are made.

And, yes, there will be a cat involved.

We’ll leave the photography to others for the most part, though. Blurry snapshots will not do for these grand old rocks.

Let’s begin in the deepest of deep time. Let’s talk schist.

Alas, I could not find a decent photograph of a Brahma Schist specimen, so this shot of schist in-situ will have to do. I can’t prove beyond reasonable doubt that the dark bit of schist I picked up by my house in Flagstaff is, indeed, Brahma Schist, but like any good suspect, it matches the general description. We’ll run with it.

The Brahma Schist is found with the Vishnu and Rama Schists, gorgeously exposed in the Grand Canyon. When you hold a piece of this schist in your hand, you’re holding nearly two billion years of history. Brahma Schist “[c]onsists of amphibolite, hornblende-biotite-plagioclase schist, biotite- plagioclase schist, orthoamphibole-bearing schist and gneiss, and metamorphosed sulfide deposits.” It was created from a variety of volcanic rocks from mafic to intermediate composition. That’s a fancy way of saying the Brahma Schist is made from volcanic islands that, due to the vagaries of plate tectonics, got squashed up against the North American continent a long time ago.

As the islands collided and ocean crust sank into the subduction zone, mountains formed and the lower part of the earth’s crust got pushed down into the squishy, near-molten mantle. Schist formed in the middle bits of this mass.

Since it came from dark volcanic rocks, the Brahma Schist is fairly dark. But schist is a variable stone, and our next specimen looks like a flaky chunk of the sun when the light hits it right. My darlings, allow me to introduce you to mica schist.

Well, actually, Jim and Ellen of Jim & Ellen’s Rock-N-Shop shall be doing the honors:

Mica schist represents the final stage of metamorphism. Just short of actual remelting, mica schist is the penultimate product of alteration, by heat, volatile gasses, and pressure, of the mixture of the hydrated and oxidized minerals in shale and muddy sandstones. The “normal” stages of the metamorphic process due to plate tectonic activities are as follows: Shale – slate – phyllite – Mica schist. Sandy shales, on complete recrystallization, will be compressed and recrystallize to a final rock that appears to be mostly mica. The mica crystals have arranged themselves so that the flat plates have grown at right angles to the crustal pressure affecting the rock. Other volatile compounds produced in this intense metamorphic environment are garnet, staurolite, andalusite and kyanite as well as bits of granite and feldspar which are not very obvious because the flat cleavage planes of mica dominate the outward appearance of the specimens.

My gorgeous hunk of mica schist comes from Mingus Mountain, which is part of Arizona’s Black Range. Mingus “exposes Precambrian, Cambrian, Devonian, Mississippian, Pennsylvanian, and Tertiary rocks.” A long history, to be sure! It’s one of the few mountains near Northern Arizona that wasn’t caused by a recent volcano going boom. Further discussions of its geology, alas, shall have to wait until I’ve finished reading up on Arizona’s geology, as no one seems to have been considerate enough to a) put up a long description online b) where Google can easily find it.

Ignorance is not bliss.

Mingus overshadows Jerome, Arizona, where you can come across all sorts of interesting and often valuable rocks. Some of the rocks aren’t even rocks as most folks understand them, but metal. Jerome owes its existence to copper, which deposits were “the result of two giant, mineral-rich hydrothermal vents that formed its ore deposits some 1.7 billion years ago.” That’s right – hydrothermal. As in, deep ocean vents. The ore bodies “occur at the top of a great pile of Precambrian submarine volcanic rocks, now so metamorphosed that they were at one time thought to be an intrusion. Some of the rocks in direct contact with the ore bodies have been dated as about 1,800 million years old.” (source) Pretty amazing to think that my little nugget of native copper from Jerome might be about as ancient as my Brahma schist.

Copper usually doesn’t appear in shiny little lumps, but in ores. One of those ores, and one of my favorite finds, is conichalcite, calcium copper arsenate hydroxide. What a mouthful, right? Here’s what Amethyst Galleries has to say about it:

Conichalcite has a sparkling grass green color that once observed is hard to mistake for any other mineral. It is often encrusted onto limonitic rocks that have a red to yellow color and the two produce a very colorful specimen. Conichalcite forms in the oxidation zone of copper ore bodies. Oxygen rich ground water that might react with copper sulfide and/or copper oxide minerals produce a wonderful assortment of attractive and colorful minerals in a zone called the oxidation zone. Conichalcite is just one of these minerals. Other oxidation zone minerals include malachite, azurite, linnarite, etc.

Conichalcite forms a solid solution series with the mineral calciovolborthite. A solid solution series occurs when two or more structurally identical minerals can interchange elements within their chemistries without dramatically altering the crystal structure. In the case of conichalcite and calciovolborthite the two elements are arsenic and vanadium. Conichalcite is the arsenic rich end member of the series and calciovolborthite is the vanadium rich end member.

My bit comes from Sonora, Mexico, but it’s also common enough around Arizona to count as an Arizona rock.

Another copper ore, bornite (copper iron sulfide), is one of the most flamboyant minerals ever. Its spectacular blues and purples are actually tarnish:

The colors are from an iridescent tarnish that forms on bornite upon exposure to air. The tarnish is made of assorted copper oxides or hydroxides that form a mere atoms thin layer over the bornite. The thickness of the layers is close to the wavelength of light. When light waves bounce between the bornite surface and the top of the tarnish layer they will leave with the wavelengths of various colors. This effect is the same as the rainbow effect that occurs with oil on water. In the case of bornite, the tarnish will have a purplish, violet or blue color. Because bornite is often intergrown with chalcopyrite which tarnishes to more greens and yellows, the peacock ore may have many colors ranging from purple to blue to green to yellow.

As you can see, it’s also considered a rather tasty treat by my parents’ cat Spook. I’m not sure it’s part of the recommended daily allowance of minerals, but I don’t think he cares.

It’s not just attractive to humans and cats, but valuable:

Bornite is an important copper ore mineral and occurs widely in porphyry copper deposits along with the more common chalcopyrite. Chalcopyrite and bornite are both typically replaced by chalcocite and covellite in the supergene enrichment zone of copper deposits. Bornite is also found as disseminations in mafic igneous rocks, in contact metamorphic skarn deposits, in pegmatites and in sedimentary cupriferous shales. It is important for its copper content of about 63 percent by mass and is found in Arizona, Butte, Montana, and Mexico.

I have no idea where my specimen came from, because the gift shop at Gold King Mine didn’t say. We’ll pretend it’s a native, then.

My next copper ore is most definitely an Arizona native, although I had to go all the way home to Washington to get it. Pima County’s not one of my usual stomping grounds in Arizona, though I’ve been down Highway 83 and passed right by the Santa Rita Mountains, where my lovely specimen of azurite hails from. It came from Gunsight Pass, close to the old ghost town of Helvetia.

First, some geology to set the scene:

Here as in many southern Arizona mountains the geologic pattern includes enigmatic thrust faults with slices of Paleozoic sedimentary rocks sitting astride or leaning up against a Precambrian core. The overthrust school subscribes to broad movement of a thin sheet of rocks from as much as 100 miles to the southwest. Thrust faulting in the Santa Ritas occurred 75 to 80 million years ago. Because their sedimentary sequence is relatively complete and only slightly deformed, these mountains contain more clues than most to the geologic history of the region. Both Paleozoic sedimentary strata and Precambrian core are intruded by Tertiary porphyry associated with scattered copper deposits. (source)

And those scattered copper deposits are sometimes given away by the presence of azurite (copper carbonate hydroxide), a gorgeous mineral formed from the weathering of copper ore:

Azurite is a very popular mineral because of its unparalleled color, a deep blue called “azure”, hence its name. Azure is derived from the arabic word for blue. The color is due to the presence of copper (a strong coloring agent), and the way the copper chemically combines with the carbonate groups (CO3) and hydroxyls (OH). Azurite has been used as a dye for paints and fabrics for eons. Unfortunately, at times its color is too deep and larger crystals can appear black. Small crystals and crusts show the lighter azure color well. Azurite is often associated with its colorful close cousin, malachite.

In fact, malachite often sneaks in and replaces azurite.

If the emphasis seems a little heavy on copper and its mineral ores, well, that’s because copper and Arizona are virtually synonymous. You can’t really throw a stone in most of the state without hitting a copper mine, or so it often seems. In fact, here’s one now:

Open pit mines became the done thing in Jerome after a little incident with chemistry and the United Verde mine back in 1894. Which, oddly enough, created yet more minerals I plan to someday get my hands on.

But let us move on from copper and all its varieties, and spend some time in Arizona’s coastal dunes. In order to do so, we’ll have to travel back in time about 262 million years, to the time when the Toroweap Formation was being deposited. The Toroweap’s a riot of rocks – sandstones, limestones and mudstones, in places even containing gypsum. Allow Ron Blakey and Wayne Ranney to set the scene (source):

Toward the end of the Early Permian, two marine transgressions finally completed the [Colorado] plateau’s Paleozoic section of rocks. Both seas entered the region, this time from the west. The first of these transgressions deposited marine, sabkha, and shoreline sediments known as the Toroweap Formation…. [In the Sedona area,] eolian shoreline environments deposited resistant, cross-bedded sandstone that laterally replaces the softer sabkha deposits. These eolian deposits form an “upper Coconino Sandstone” (or “sandy Toroweap Formation,” take your pick) in Northern Arizona (Oak Creek Canyon…).”

Below it, sometimes mingling with it, the Coconino Sandstone is a huge erg (dune field) deposit that indicates Arizona was once a sea of sand. It’s 500 to 1000 feet thick, cream or pale golden-colored sandstone formed after the ancient Pedregosa Sea retreated 265 million years ago. In places in Oak Creek Canyon, you can see its exquisite cross-bedding, showing that it’s basically petrified dunes. It forms a nice white counterpoint to the tans and pale reds of the Toroweap Formation, and yes, thank you, all of them look wonderful in my collection.

Since the fragments I picked up were rather too wee to photograph well, and online sources are more excited about cliffs than specimens, you’ll just have to content yourselves with a photo of me collecting bits of the two formations:

Exciting, right? Just imagine walking alongside a road with no shoulder and hairpin turns just because you’re determined to get yourself a piece of Oak Creek Canyon, and you might find it a bit more entertaining. Yes, I’m obsessive.

The final piece in the collection I shall subject you to today, so unique that I must force my foul photography upon you, is a bit of a mystery, because I picked it up from the Dry Beaver Creek stream bed along Highway 179 back in the 90s. Being that it’s obviously been swimming, it could be a piece of anything. It could be a hunk of the Hermit Formation, which includes red and white cross-bedded calcareous sandstone and siltstone. The Hermit was formed from fluvial redbeds, a fancy way of saying that large river systems spread a bunch of sediment around an arid landscape. It could be a chunk of the Schnebly Hill formation along with a bit of Coconino Sandstone. Or it might be a bit of the Supai Group, with the white bits bleached by submersion in a less fickle water source than Dry Beaver Creek. You can read up on Sedona-area geology and take your pick. No matter what it is, holding it in hand reminds you that Arizona’s gone through a lot of interesting changes in its (in places) 2-billion year history.

And you can read all about it in the rocks.

(As always, click the pics for sources. If all you get is a ginormous version, that means I’m the one responsible. My apologies.)

Sunday Sensational Science

Hubble Rejuvenated

Thanks to Darksyde at Daily Kos, thee shall have gorgeous new Hubble Space Telescope images to drool over. Most of you know that Hubble got an upgrade back in May. The cameras are now calibrated, and Hubble’s back to providing breathtaking images and scientific insight into the cosmos that was unimaginable before it launched.

Even before calibration was finished, Hubble ended up snapping away. It’s not every day that you get a chance to capture the impact of an asteroid on Jupiter – the last time was comet Shoemaker-Levy 9 a decade and a half ago. What’s an astronomer to do – keep fiddling the instruments until all is perfection, or say bugger perfection and capture something really incredible?

We all know the answer to that one:

24-Jul-2009: The checkout and calibration of the NASA/ESA Hubble Space Telescope has been interrupted to aim the recently refurbished observatory at a new expanding spot on the giant planet Jupiter. The spot, caused by the impact of a comet or an asteroid, is changing from day to day in the planet’s cloud tops.

For the past several days the world’s largest telescopes have been trained on Jupiter. Not to miss the potentially new science in the unfolding drama 580 million kilometres away, Matt Mountain, director of the Space Telescope Science Institute in Baltimore, Maryland, allocated discretionary time to a team of astronomers led by Heidi Hammel of the Space Science Institute in Boulder, Colorado.

The Hubble picture, taken on 23 July, is the sharpest visible-light picture taken of the feature and is Hubble’s first science observation following its repair and upgrade in May. Observations were taken with Hubble’s new camera, the Wide Field Camera 3 (WFC3).


Since we believe this magnitude of impact is rare, we are very fortunate to see it with Hubble“, added Amy Simon-Miller of NASA’s Goddard Space Flight Center. She explained that the details seen in the Hubble view show a lumpiness to the debris plume caused by turbulence in Jupiter’s atmosphere. The spot is presently about twice the length of the whole of Europe.

Simon-Miller estimated that the diameter of the object that slammed into Jupiter was at least twice the size of several football fields. The force of the explosion on Jupiter was thousands of times more powerful than the suspected comet or asteroid that exploded over the Tunguska River Valley in Siberia in June 1908.

So there was that excitement. After that, calibration continued, and I think you’ll all agree the results were worth a spacewalk for:

The NASA/ESA Hubble Space Telescope’s newly repaired Advanced Camera for Surveys (ACS) has peered across almost five billion light-years to resolve intricate details in the galaxy cluster Abell 370. Abell 370 is one of the very first galaxy clusters where astronomers observed the phenomenon of gravitational lensing, the warping of space-time by the cluster’s gravitational field that distorts the light from galaxies lying far behind it. This is manifested as arcs and streaks in the picture, which are the stretched images of background galaxies.

These two images of a huge pillar of star birth demonstrate how observations taken in visible and in infrared light by the NASA/ESA Hubble Space Telescope reveal dramatically different and complementary views of an object.

The pictures demonstrate one example of the broad wavelength range of the new Wide Field Camera 3 (WFC3) aboard the Hubble telescope, extending from ultraviolet to visible to infrared light.

This celestial object looks like a delicate butterfly. But it is far from serene.

What resemble dainty butterfly wings are actually roiling cauldrons of gas heated to nearly 20 000 degrees Celsius. The gas is tearing across space at more than 950 000 kilometres per hour — fast enough to travel from Earth to the Moon in 24 minutes!

A dying star that was once about five times the mass of the Sun is at the centre of this fury. It has ejected its envelope of gases and is now unleashing a stream of ultraviolet radiation that is making the cast-off material glow. This object is an example of a planetary nebula, so-named because many of them have a round appearance resembling that of a planet when viewed through a small telescope.

The Wide Field Camera 3 (WFC3), a new camera aboard the NASA/ESA Hubble Space Telescope, snapped this image of the planetary nebula, catalogued as NGC 6302, but more popularly called the Bug Nebula or the Butterfly Nebula.

A clash among members of a famous galaxy quintet reveals an assortment of stars across a wide colour range, from young, blue stars to aging, red stars.

This portrait of Stephan’s Quintet, also known as the Hickson Compact Group 92, was taken by the new Wide Field Camera 3 (WFC3) aboard the NASA/ESA Hubble Space Telescope. Stephan’s Quintet, as the name implies, is a group of five galaxies. The name, however, is a bit of a misnomer. Studies have shown that group member NGC 7320, at upper left, is actually a foreground galaxy that is about seven times closer to Earth than the rest of the group.

Using a distant quasar as a cosmic flashlight, a new instrument aboard the NASA/ESA Hubble Space Telescope has begun probing the invisible, skeletal structure of the Universe.

Called the cosmic web, it is the diffuse, faint gas located in the space between galaxies. More than half of all normal matter resides outside of galaxies. By observing the cosmic web, astronomers can probe the raw materials from which galaxies form, and determine how this gas was assembled into the complex structures of the present-day Universe.

Using the light from the quasar PKS 0405-123, located 7.8 billion light-years away, the newly installed Cosmic Origins Spectrograph (COS) on Hubble probed a string of gas clouds residing along the light path at different distances. Quasars are the bright cores of active galaxies and are powered by supermassive black holes. Thousands of quasars have been observed, all at extreme distances from our Milky Way galaxy. The most luminous quasars radiate at a rate equivalent to a trillion Suns.

The COS spectrum shown here reveals the absorption lines of elements that make up the intervening gas clouds traversed by the quasar’s light. COS detected three to five times more lower-density filaments of hydrogen in the cosmic web than were seen in previous observations along this line of sight. The instrument also detected evidence of glowing oxygen and nitrogen that predominantly trace strong shocks in the filamentary cosmic web. These shocks are produced by gravitational interactions between intergalactic clouds of gas falling onto filaments in the web and by the fast outflow of material from star-forming galaxies.

Rings of brilliant blue stars encircle the bright, active core of this spiral galaxy, whose monster black hole is blasting material into space at over 14 million kilometres per hour. Viewed nearly face-on, the galaxy, called Markarian 817, shows intense star-forming regions and dark bands of interstellar dust along its spiral arms. Observations by the new Cosmic Origins Spectrograph (COS) aboard the NASA/ESA Hubble Space Telescope captured the powerful outflow of material from this galaxy.

The signature balloon-shaped clouds of gas blown from a pair of massive stars called Eta Carinae have tantalised astronomers for decades. Eta Carinae has a volatile temperament, and has been prone to violent outbursts over the past 200 years.

Observations by the newly repaired Space Telescope Imaging Spectrograph (STIS) aboard NASA’s Hubble Space Telescope reveal a stream of charged particles from a massive stellar wind and some of the chemical elements that were ejected in the eruption seen in the middle of the nineteenth century.

STIS resolved the chemical information along a narrow section of one of the giant lobes of ejected material. In the resulting spectrum, iron and nitrogen define the outer material cast off in the nineteenth century from Eta Carinae. STIS also reveals the interior material being carried away by the ongoing wind from Eta Car A, the primary star. The amount of mass being carried away by the wind is the equivalent of one Sun every thousand years.

Plenty more where that comes from, my darlings, including videos. Enjoy!

Sunday Sensational Science

Volcanoes From Space

George at Decrepit Old Fool sent me a link to Wired Science’s spectacular article on satellite images of volcanoes. Many of them were shot from space shuttles and the International Space Station. They’re not the only sources, though – satellites have snapped some amazing pictures themselves.

When we think of NASA, we usually think outer space – but NASA frequently turns its electric eyes Earthward. The results are spectacular. And they help us understand Earth in ways impossible before the space age.

The following three sets of images and words are all from the article.

Many of the stunning images of eruptions captured from space are of violent stratovolcanoes, such as the one above of Kliuchevskoi, the most active volcano on Russia’s Kamchatka peninsula. The image above was taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash plume reached as high as 50,000 feet.

Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.

The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising and cooling of the air above. In contrast, a dark gray cloud of ash near the ground is probably an avalanche of hot ash and rock known as a pyroclastic flow.

Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in this picture are from forest fires ignited by lava.

Earth, of course, isn’t the only tectonically active world in our solar system. Some moons still feature volcanic eruptions; planets like Venus and Mars host some of the most incredible extinct volcanoes around. Did I say extinct? Maybe they’re merely sleeping. Read on…

March 9, 2007: Andy Cheng has seen it all. The scientist from Johns Hopkins’ Applied Physics Lab has worked on the Galileo mission to Jupiter, the Cassini mission to Saturn, the NEAR mission to asteroid 433 Eros and many others during his decades-long career. Alien vistas are old hat to him. But even he was amazed when he laid eyes on this photo of Io’s Tvashtar volcano, taken Feb. 28th by the New Horizons spacecraft.


Tvashtar’s plume dwarfed grand old Prometheus, rising 180 miles (290 km) above Io’s surface. (For comparison, volcanoes on Earth spew their gas and dust just a few miles high.) “The patchy and filamentous structure seen in the Tvashtar plume suggests to me that condensation from gas to solid particulates is occurring,” he says. In other words, the gas could be crystallizing in the cold space above Io to form a kind of sulfurous snow.

Volcanoes spewing snow? It is an alien world.

This image, acquired during Galileo’s ninth orbit around Jupiter, shows two volcanic plumes on Io. One plume was captured on the bright limb or edge of the moon, erupting over a caldera (volcanic depression) named Pillan Patera. The plume seen by Galileo is 140 kilometers (86 miles) high, and was also detected by the Hubble Space Telescope. The second plume, seen near the terminator, the boundary between day and night, is called Prometheus. The shadow of the airborne plume can be seen extending to the right of the eruption vent. (NASA/JPL/University of Arizona)

The Hubble Space Telescope has snapped a picture of a 400-km-high (250-mile-high) plume of gas and dust from a volcanic eruption on Io, Jupiter’s large innermost moon.

Io was passing in front of Jupiter when this image was taken by the Wide Field and Planetary Camera 2 in July 1996. The plume appears as an orange patch just off the edge of Io in the eight o’clock position, against the blue background of Jupiter’s clouds. Io’s volcanic eruptions blasts material hundreds of kilometers into space in giant plumes of gas and dust. In this image, material must have been blown out of the volcano at more than 2,000 mph to form a plume of this size, which is the largest yet seen on Io.

Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Ice geysers erupt on Enceladus, bright and shiny inner moon of Saturn. Shown in this false-color image, a backlit view of the moon’s southern limb, the majestic, icy plumes were discovered by instruments on the Cassini Spacecraft during close encounters with Enceladus in November of 2005. Eight source locations for these geysers have now been identified along substantial surface fractures in the moon’s south polar region. Researchers suspect the geysers arise from near-surface pockets of liquid water with temperatures near 273 kelvins (0 degrees C). That’s hot when compared to the distant moon’s surface temperature of 73 kelvins (-200 degrees C). The cryovolcanism is a dramatic sign that tiny, 500km-diameter Enceladus is surprisingly active. Enceladus ice geysers also likely produce Saturn’s faint but extended E ring.

This is a shaded relief image derived from Mars Orbiter Laser Altimeter data, which flew onboard the Mars Global Surveyor. The image shows Olympus Mons and the three Tharsis Montes volcanoes: Arsia Mons, Pavonis Mons, and Ascraeus Mons from southwest to northeast. Print-resolution copy Credit: NASA

New research raises the possibility that Mars could awaken from within — three large Martian volcanoes may only be dormant, not extinct. Volcanic eruptions release lots of greenhouse gasses, like carbon dioxide, into the atmosphere. If the eruptions are not complete, and future eruptions are large enough, they could warm the Martian climate from its present extremely cold and dry state.

NASA-funded researchers traced the flow of molten rock (magma) beneath the three large Martian volcanoes by comparing their surface features to those found on Hawaiian volcanoes.

“On Earth, the Hawaiian islands were built from volcanoes that erupted as the Earth’s crust slid over a hot spot — a plume of rising magma,” said Dr. Jacob Bleacher of Arizona State University and NASA’s Goddard Space Flight Center in Greenbelt, Md. “Our research raises the possibility that the opposite happens on Mars – a plume might move beneath stationary crust.” The observations could also indicate that the three Martian volcanoes might not be extinct.

The volcano Maat Mons is displayed in this computer generated three-dimensional perspective of the surface of Venus. Radar data is combined with radar altimetry from NASA’s Magellan mission to develop a three-dimensional map of the surface. The viewpoint is located 634 kilometers (393 miles) north of Maat Mons at an elevation of 3 kilometers (2 miles) above the terrain. Lava flows extend for hundreds of kilometers across the fractured plains shown in the foreground, to the base of Maat Mons. The vertical scale in this perspective has been exaggerated 10 times. Simulated color and a digital elevation map developed by the U.S. Geological Survey are used to enhance small-scale structure. Print-resolution copy (1 meg jpg image) Credit: NASA/JPL

This cluster of four overlapping domes is located on the eastern edge of Alpha Regio. The domes average about 25 kilometers (16 miles) in diameter with maximum heights of 750 meters (2,460 feet). These features can be interpreted as viscous or thick eruptions of lava coming from a vent on the relatively level ground allowing the lava to flow in an even lateral pattern.

Images and discoveries like these make me damned grateful to have been born in the last quarter of the 20th Century. Perhaps, if we’re extremely lucky and astronomers find a planet suitably close, we’ll even live to see the first images of a volcano erupting in another solar system. How’s that for sensational?

For more outstanding images of volcanoes in action, check out this link.

Sunday Sensational Science

Touring Lowell Observatory

Most people visit Flagstaff for the Grand Canyon, skiing, hiking, and other outdoor activities. But about 70,000 folks a year take a detour from downtown Flagstaff, climb a nondescript Ponderosa-covered hill, and go play with science instead.

Lowell Observatory’s a family affair. It’s been privately owned since Percival Lowell built it in search of Martian canals in 1894 – his grandnephew’s the current trustee. It’s among the oldest observatories in the United States. And it’s a fantastic place to experience science and history all in one go.

I’ve already written about Lowell Observatory’s contributions to science. In this edition of Sunday Science, we’ll just have a walk around the grounds, get to know some of the quirks and oddities of the place, and get our hands on history.

Once you pass through the Visitor’s Center, you enter a courtyard surrounded by venerable old buildings. And you’ll see something that looks like a sculpture of a telescope. It’s a work of art, all right, but it’s the real deal – the 42-inch reflecting telescope built by Alvin Clark & Sons. Lowell wanted a reflector for planetary observations, and he certainly got it. The 11-ton giant was installed in a dome in 1909, and remained in active use until the late 1960s, when it was replaced by a new 42-inch reflector made of low-expansion glass, installed at Anderson Mesa.

Dr. Slipher used it for spectroscopic studies for about two years; his brother Earl used it to take Kodachrome photographs of the planets (I did mention Lowell’s a family affair, right?). But for the majority of its working life, it was C.O. Lampland’s baby. Dr. Lampland used it to take over 10,000 pictures of spiral nebulae (later discovered to be galaxies), star clusters and star fields. He and colleague W. W. Coblentz used the telescope to measure the surface temperatures of Mars, Venus and other planets – their work helped establish that Mars has a very thin atmosphere indeed. And after Pluto’s discovery, Dr. Lampland aimed this telescope at it and got accurate positions for it, essential in determining its orbit.

All this happened, of course, before the poor reflector got retired and chucked out of its dome to serve as a work of astronomical art.

Look at it in relation to the Visitor’s Center behind it, and realize one thing: it is huge. Very, very huge. Staring at things very far away requires big equipment.

And big equipment requires big domes. This is the home sweet home of the 24-inch Clark Telescope. This is the centerpiece of the Observatory. It dominates Mars Hill. It acts like a gravity well: you make little circular motions trying save it for later, but you spiral closer and closer until you finally just give up and make a beeline for it. There’s a reason why the Observatory tour guides usually take you there first.

On clear nights, a long line of folks snakes out of the building, down the steps and out into the courtyard, waiting for their turn to gaze through the eyepiece at the cosmos. On the night we went, they had the Clark aimed at the Moon. You have not truly experienced our nearest cosmic neighbor until you’ve viewed it through the lens of a large telescope – the mountains and craters pop out in vivid relief, starkly outlined along the edge against the blackness of space. The Moon’s brilliant white glow, dimmed by dark maria, so clear and sharp you feel you could step through and touch it, fills your vision. It’s tough to pull yourself away and let the next visitor take their turn. But there’s plenty to look at even when you’re not looking through the telescope.

The dome alone weighs 8 tons. The walls and supports are soft golden pine, giving the telescope’s home the feel of a no-frills pioneer’s house. And yes, those are truck tires up there. The dome is rolled about on one particular variety of tire – 1954 Ford pickup tires, to be precise. They do a better job and make a lot less noise than the old iron wheels in use before. Of course, every once in a while, one of them pops with a gawdawful bang, and they’re not fancy, but when you’re a privately-owned observatory that has the choice between spending scarce funds on fancy-schmancy extras and funneling those funds into the really essential stuff, you put up with the occasional blown tire.

And if you’re the proud owner of some extra 1954 Ford pickup truck tires, there are some folks at the Observatory who’d like to have a chat with you.

But truck tires aren’t the most amusing improvisation in the dome. Follow the arrow in the next photo and see if you can identify the lens cap for the guide telescope on the side of the refractor:

Why, yes, indeed, it is Mrs. Lowell’s frying pan. She’d just gotten a new set when Mr. Lowell needed a lens cap and discovered that a frying pan is precisely the right size and shape to get the job done. Needless to say, she wasn’t exactly thrilled when she discovered where her new pan had got to.

For your entertainment, the guide will show you the cover. It settles over the lens of the guide scope with a satisfying culinary bang.

The Clark itself is a bit more sophisticated. The instrumentation is the real deal, not pieces cobbled together from kitchens and cars. It’s made of rolled steel, weighing in at a slim 6 tons, and is 32 feet long. It’s so well-mounted that you can move it with a touch. Lowell hooked spectrographic equipment up to it in 1901. Lowell used it as his primary instrument in his Martian investigations; V.M. Slipher employed it to measure the redshifts of galaxies, giving him one of the first looks at the expanding universe.

The Clark’s been in use since 1896. It started its career in Mexico, where Lowell had it erected in December of 1896 that provided a better view of the opposition of Mars. It came home to Mars Hill shortly afterward. Its main function today is to give visitors an astronomer’s-eye view of the cosmos. There’s something particularly thrilling about stepping up and looking through the same instrument used by famous astronomers like Lowell and Slipher. If you get the chance, you really must experience it for yourself.

Then head on over to the Rotunda Museum for a look at history. It’s in the Slipher Building’s Rotunda Library. The building’s fascinating for its architecture as well as its science – it was most likely designed by Percival and Constance Lowell themselves. The dome was intended to resemble Saturn, with a thin balustrade standing in for the rings. The balustrade never happened, but the dome certainly did. They aligned the building with the spring and autumn equinoxes for an extra astronomical touch.

Mrs. Lowell did a hell of a job with the interior. She designed a large “arts and crafts” fireplace on the north wall (it’s arts-and-crafts the way a painting is a doodle), and she ordered the stained glass light fixture in the shape of – what else? Saturn:

Note the graceful spiral staircases, the elegant library circling the open second floor, the windows inviting in all that gleaming Arizona sun:

And then keep in mind that this was designed and built as an office building. They knew how to marry form, function and sophistication back in the early 20th Century, didn’t they just?

It’s all crowded with relics, as you can see from the above photos. When you visit, you’ll get a chance to see Percival Lowell’s first telescope, a 2.25 inch brass beauty his mother gave him on his 15th birthday:

From such gifts, life paths are chosen.

Among the displays, you’ll get to see Clyde Tombaugh’s log of observations. The photo below shows his log book of the plates from 1930, wherein Pluto was revealed:

And the equipment he used to make those plates:

Pretty intriguing stuff. If you’ve ever wondered how astronomers managed to make important discoveries pre-computerized equipment, this is an excellent place to learn. You’ll see examples of all sorts of equipment that did the job before the silicon chip was even dreamt of.

Lowell himself never got to see Pluto’s discovery, or even enjoy his sunny new office in the Slipher Building. He died in 1916. But he got to stick around. Mrs. Lowell had a massively expensive mausoleum built for him, complete with cobalt tiles and Italian building stone. She also decided that her share of the will wasn’t quite enough, and so she went to court to obtain the rest. The ensuing legal battle ate half of the Observatory’s $2.3 million inheritance, and to this day, you’ll still hear Mrs. Lowell blamed for the Observatory’s every financial woe.

So it goes. Families are messy things, and they sometimes tear themselves apart. Mrs. Lowell lost her fight and faded from the scene. The science went on while Lowell lay sleeping. Pluto got discovered, which has given them lasting fame even after the poor “planet” got demoted. Today, Lowell Observatory’s much more than Mars hill – there’s it’s Anderson Mesa facility, where important projects like the Little Things Survey and Local Group Survey are in full swing. And by 2011, the Discovery Channel Telescope will be online in Happy Jack. The Observatory’s thriving, and at least everybody got an interesting Mausoleum out of the bargain.

It could’ve been worse.

Just yesterday, the Arizona Republic ran an article about Lowell and his wonderful Observatory. Reporter John Stanley summed up Lowell’s career thusly:

Although Lowell was grossly mistaken about the markings on Mars, his theories inspired generations of scientists, engineers, writers and filmmakers. He also was wrong about Planet X, yet his calculations led to the discovery of Pluto. Sometimes that’s the way science works.

That is indeed. Percival Lowell left one hell of a legacy. And if you get a chance to go see it for yourselves, you’ll see the inspiration he left for future astronomers, not only in the work and the equipment he left behind, but in his own words, which you’ll find on his Mausoleum wall:

That, at the end of the day, is just what science is all about.

Further Reading:

For descriptions of the telescopes and a history of Lowell, see V.M. Slipher’s own article in Publications of the Astronomical Society of the Pacific. There’s also useful information in this rough draft of the article “The Telescopes of Lowell Observatory.”

A good photo tour with fun snippets can be found here. A 360-degree tour for those who can’t make it to Arizona is available here.

The architecture and history of the Slipher Building can be found in this Historic American Building Survey by the National Park Service (.pdf).

(A Poor Excuse for) Sunday Sensational Science

Mea culpas are in order, my darlings. I meant to have a spiffy article on Meteor Crater put together in honor of the Perseid Meteor Showers. That, obviously, did not happen, as you’re reading my sorry excuses instead.

It’s been a bad week. It started with Aunty Flow, who allowed me just enough energy and respite from the pain to keep up with normal posting, but no more. It finished with The Stench.

I have been battling The Stench since Thursday. It’s consumed the majority of my attention. It’s prevented me from getting a proper night’s sleep for days. It has sent me to the store repeatedly for anti-Stench items, such as Glade’s Febreeze ripoff (damn you, Target, for being out of the real thing!).

That’s right. I bought a memory foam mattress topper. And the smell is everything you’ve been warned about and more. It resembles gasoline crossed with the toxic goo that created the Joker. It is, above all, pervasive.

I’ve tried airing the damned thing out on the porch, but in Seattle, you can only leave things outside so long before the damp destroys them. I’ve tried covering it with layers upon layers of thick, heavy blankets. I’ve tried dryer sheets. I’ve tried blasting it with fans. I’m finally reduced to a waterproof mattress protector, which worked for a few hours. But The Stench is now starting to penetrate even that, along with the thick mattress pad, the blankets, and about ten thousand dryer sheets.

It’s terribly distracting, and combined with the social life I developed over the weekend, has led me to punk off Sunday Science until it’s too late for anything complicated.

You may ask why I’ve not chucked the memory foam mattress topper into the nearest dumpster. Three reasons. One, the thing’s hideously expensive and nearly impossible to return. Two, The Stench is not long for this world – memory foam loses its odor in a few days to a few weeks. Three, once The Stench is gone, bliss will be mine all mine. The topper’s not quite a Tempurpedic, but it’s damned comfortable. Far better than the ancient feather mattress I’ve been using.

It will all be worth it in the end. But if you decide to buy one of these things, make sure it can have a room of its own for a few weeks. And buy it in a season when you can have the windows open.

But enough of The Stench. Let’s talk my social life, which involved some science. Our local skeptics group decided to meet on a Saturday for all us poor bastards who can’t make it to the meeting on Tuesday nights. We were discussing the Apollo moon landing, and the idiots who to this day believe it’s a hoax.

We watched a “documentary” called A Funny Thing Happened on the Way to the Moon. My darlings, grab your local skeptics and pirate a copy forthwith. It’s hilarious. It starts out with Bible quote after Bible quote. It continues with a discuss of the Tower of Babel and the Titanic (which, it’s implied, God hisownself sank). It has a musical interlude with a bunch of rockets blowing up, followed by a smorgasboard of arguments from incredulity, logical fallacies, spectacular ignorance of basic physics and photography, and arguments from the Kennedy assassination. Even Godwin’s there in spirit. If you could stick posts from the DIsco Institute, Answers in Genesis, and other such luminaries of dumbfuckery into a blender with Expelled and Ray Comfort’s banana video, puree on high for two minutes, and then turn the resulting blend into a DVD, it would emerge as something very like this “documentary.”

There’s only one way to follow that up: the Mythbusters Moon Hoax special. You can view clips here. Or just get your local skeptics together – there’s nothing quite like a room full of very smart, very skeptical, and very knowledgeable people taking these myths apart one by one.

The only thing missing was a video of Buzz Aldrin punching the moon hoax moron in the nose.

So, anyway, that’s what’s keeping you from getting an honest-to-goodness Sunday Sensational Science this week. But there’s a little science for you – I’ve got some follow-up to Kepler’s launch.

First off, the thing works – it really works!

And that’s what the news is from Kepler. As a test of its abilities, it observed the star known as HAT-P-7, which is known to have a roughly Jupiter-sized world orbiting it every 2.2 days. This planet, called HAT-P-7b, is far too close to the star to be seen directly, but every time it passes in front of the star, the light we see drops. Here’s what Kepler saw after observing this system for 10 days:

Kepler observations of HAT-P-7B

The top plot shows the data as the planet circles the star. The big dip is due to the planet blocking a fraction of the star’s light. The depth of that dip tells us how much of the star was blocked, and therefore the size of the planet. But look along the plot a little bit to the right: see that fainter dip (right under the i in “Magnification”)? What’s that?

The bottom plot is the same thing but zoomed in to see more detail. That second dip is a lot more obvious. It’s not another planet blocking starlight, which is what you might first guess. It’s actually the light from the planet being blocked by the star!

The planet is reflecting light from the star, just like the Moon reflects sunlight, allowing us to see it. When the planet passes behind the star, we don’t see that light anymore, so the total light from the system drops a wee bit. It’s not much, and totally impossible to see from the ground, but Kepler was able to spot it. And that’s critical, because it turns out this dip is about the same thing we’d expect to see if a planet the size of the Earth were to pass in front of the star. In other words, the drop in light from a giant planet going behind its star is about the same as we’d expect from a smaller planet passing in front of the star.

The fact that Kepler spied this dip at all means that, if somewhere out there an Earthlike world is orbiting a star, Kepler will be able to detect it!


And, as Darksyde noted last week, it even managed to detect its first exoplanet atmosphere:

NASA’s new exoplanet-hunting Kepler space telescope has detected the atmosphere of a known giant gas planet, demonstrating the telescope’s extraordinary scientific capabilities. The discovery will be published Friday in the journal Science.

“As NASA’s first exoplanets mission, Kepler has made a dramatic entrance on the planet-hunting scene,” said Jon Morse, director of the Science Mission Directorate’s Astrophysics Division at NASA Headquarters in Washington. “Detecting this planet’s atmosphere in just the first 10 days of data is only a taste of things to come. The planet hunt is on!”

Good hunting, Kep!

Sunday Sensational Science

Arizona Botany: El Norte

Last week, we traveled through Southern and Central Arizona, munching our way through various cacti, soaping our hair with yucca plants, and shading under the lovely sycamores. At last, we’ve reached Northern Arizona, which always shocks the hell out of people who’ve seen nothing of Arizona but dirt, desert, and dessicated plants.

Northern Arizona’s got a lot of green, my darlings. But we’ll ease you in with a denizen of the more sparsely-foliaged frontiers.

Lavender-leaf Sundrops (Calylophus lavandulifolius)

Most of us Arizona denizens just call it that one yellow flower, not to be confused with that other yellow flower, but you can also call it a Lavender-leaf Primrose if you like. These delightful little blooms like to rough it in dry, rocky territory. You can find them on hillsides, ledges, eroded stream valleys, roadsides, forest clearings, and disturbed ground anywhere from just over 4,000 to almost 8,000 up.

This one’s growing at Meteor Crater. Talk about your disturbed ground! It’s one of the few plants braving the violent wind, sun and rock of the rim.

I know the first thing that comes to mind upon seeing it isn’t “Oh, hey, look – dinner!” But we’re not natives. It puts out little cylindrical seed pods about 1/2″ – 1″ long, which Apache children cooked and ate. No report on flavor, alas.

Just goes to show that most plants are more useful than we think, and kids will try anything as long as their parents aren’t the ones serving it.

Let’s visit one of the Lavender-leaf’s relatives next.

Crownleaf Evening Primrose (Oenothera coronopifolia)

If, as some claim, Arizona is hell, there is indeed a primrose path to it. These delicate-appearing beauties were a ubiquitous feature of my growing up – we had a huge bank of them growing wild along the front of our house. This is where I learned that moths pollinate flowers. We kids used to lurk outside after dark, when the evening primroses were glowing in the moonlight, and watch ginormous moths of the Schinia family cluster around like gastronomes at a gourmet food fest.

These beauties seem to like it just about anywhere. They’ll grow in poor soils, like the above bed of cinders near Red Mountain. They’re equally happy in the woods, the yard – basically anywhere they can get a toehold, you’ll find them in Flagstaff. They’re not too fascinated with competition, though – expect them in poorer soils and as first colonizers who are happy to move on when others move in.

The Oenothera family made their way up from Central America and Mexico, and variations on the theme are now found just about everywhere. The crownleaf seems to like the Southwestern states the best, but it’s found as far north as Idaho, and as far east as Kansas.

The Navajo seem to have found many uses for it, ranging from an additive for improving the flavor of wild tobacco to a stomach remedy to a poultice for swelling.

If you’re having tummy troubles, maybe we should stay on the subject of flowers.

Apricot Globemallow (Sphaeralcea ambigua)

Due to a confusion of common names, I spent my childhood wondering how Native Americans painted with this awesome little flower. This isn’t Indian Paintbrush, but it certainly painted my landscape – this plant’s ubiquitous throughout central and northern Arizona. When it bloomed in spring, we almost always had a few sprigs of it in a vase. It usually blooms orange, but it can be all sorts of colors, including purple.

Like most Arizona plants, it does just fine in poor soils, but if you get it a prime spot, you may just end up with a five-foot bush. It grows up to two feet tall. And it doesn’t mind mixing it up with other plants, as you can see from this photo, taken at the Grand Canyon.

Like the primrose, it was used by Native Americans for a variety of swellings and upset tummies. It also found itself used as a contraceptive. If you’re trying to avoid breeding, I wouldn’t necessarily test its powers in that regard – unless you’re relying on its properties as an irritant. Its stellate hairs, possibly evolved to discourage herbivores from seeing it as a banquet, aren’t easy on the eyes.

Speaking of herbivores, let’s turn next to an unlikely food source for the buggers.

Stansbury Cliffrose (Purshia stansburiana)

You’ll find these gorgeous tree shrubs clinging to cliffs, mixed happily with the trees in rocky areas, and generally beautifying the landscape. They have a sharp but pretty odor that seems to permeate the entire area when they get hot. But local browsers don’t appreciate it for it’s smell – they think it tastes great. Everything and its brother on hooves eats it, from the mule deer to bighorn sheep. It’s the winter forage in northern Arizona, even though it’s a bit bitter.

The Hopi also found it useful, although not so much as a snack. They used it as a wound wash, cough syrup, and emetic. Their Snake Priests wore kilts made of its bark. The bark also came in useful as padding for cradle boards, which I’m sure the kids appreciated. The Navajo pound its leaves and stems together with juniper to make a tan or yellow-brown dye.

It’s sometimes a life-saving plant. Being rooted firmly near cliffs, I myself utilized it more than once as an impromptu anchor. Beautiful and utilitarian – that’s the cliffrose.

But if you’re hungry, it’s time to go climb a tree.

Twoneedle Piñon (Pinus edulis)
Other people spent insane amounts of money on pinenuts in grocery stores. We just headed into the woods and shook down the cones. We’d come out with sacks of piñon nuts, which can be eaten raw, roasted, and constantly. Yum!

You can eat the sap, too. Not so yum. Never tried making piñon needle tea, but since the needles tasted pretty good when we chewed them, I don’t imagine that’s as bad as the sap.

Folks apparently use the sap for a variety of things, from salve to sunblock to splinter-removal. If only we’d known about the splinter-removal as kids!

These little guys are hardy. They’re usually found mixed with juniper around the 5,000-6,500 elevations in Arizona and New Mexico. They grow slow and grow old – a one-foot trunk may have taken 200 years to reach that size, and the tree might see another 300 years of life. This one at the Grand Canyon shows they’re not afraid of precipitous drops. They’ll work their way into cracks in the rock and grow out over the edge as if it’s nothing.

They’re actually New Mexico’s state tree. They’re practically Northern Arizona’s official Christmas tree. I know they’re my favorite tree in the universe, simply because they were my close companions growing up. There’s something friendly about a piñon forest. Maybe it’s because they’re smaller, and utterly perfect for climbing.

But not every tree in northern AZ is small. In fact, some are quite huge indeed. Prepare to meet the ultimate in Arizona pine trees.

Ponderosa Pine (Pinus arizonica)

Ponderous they are. They can reach up to 227 feet in height and 290 inches in girth. That is huge.

Height isn’t the only thing that will allow you to identify one of these. There are the needles, which are also huge. They’re 5-9 inches in length. That is long enough to make a decent broom. The loose, dry needles fallen from the trees also clump well, which for kids means prime building material for fort walls. Adults more often use the actual wood.

Native Americans ate the seeds and the sweet inner bark; used the pitch as glue, torch fuel, and rubbed it inside flutes and whistles to improve the tone. You can also make a blue dye from the roots.

Ponderosa forests are home to a variety of critters, some who browse their needles, seeds, and so forth, others who use them as shelter.

Now, one of the most awesome things about the ponderosa is its bark. If you get up close, you’ll see it’s an almost burnt-orange color, with black fissures. If you’re careful, you can peel off flakes of it that look almost like puzzle pieces. If you stick your nose deep within one of those fissures and inhale deeply, you’ll smell an aroma that in some trees is reminiscent of vanilla, in others much like chocolate. Ponderosa pines are some of the best-smelling trees in the world.

They grow in elevations mostly above 7,000 feet. We had one lonely ponderosa growing in our piñon forest, and there are areas like Sunset Crater where they mingle quite a bit, but they like the high, cool, and fairly wet spots. There’s just one problem: they’re a bit lazy. At Sunset Crater, where the rains don’t sink much past the cinders, they spread out enormous, shallow root systems that leave them vulnerable to the next high wind. So, that solid-seeming tree to your right could end up nothing but a tangled bunch of exposed roots come next gale. Amazing, eh?

Well, my darlings, we’ve barely scratched the surface of Arizona’s flora, but here our exploration ends. You can at least identify enough of Arizona’s denizens to impress folks who think of the state as nothing but trackless desert. And if you’re caught out in the wild, at least you’ll feast rather than famine, right?

Sunday Sensational Science

Arizona Botany

No, I’m not having you on. Arizona is not a trackless desert – well, it was in the early Jurassic, but you won’t find endless fields of sand dunes now. What you will find is plants – lots and lots of plants. Even the desert gets awfully green.

I’ll introduce you to a few of Arizona’s ubiquitous plants, so you can impress your friends with the news that Arizona contains plenty of botany, and you even know their Latin names.

Let’s begin in the desert and work our way north, considering that’s how most people see the state.

Palo Verde (Parkinsonia microphylla)

The Sonoran Desert contains plenty of green growing things, some so green even their bark is green. And that’s what palo verde means – green stick. Any self-respecting wash is going to have a crowd of them hanging about. They’re so ubiquitous they’ve become the state tree.

Palo Verdes adapted to desert conditions by shedding their leaves in extremely hot, dry periods. But they don’t quite go dormant – they’re still busily photosynthesizing in their bark. That lovely green hue in their trunk and branches is caused by chlorophyll. Hard-working trees, no?

If the spring’s suitably wet, the trees flower, and then put out seeds in long pods. They don’t fall from the branches. As they dry out, they pop like firecrackers. If you stand in a grove of them, you’ll swear somebody’s playing with snap-caps. Rodents run off with the seeds and bury them underground, just like squirrels do with acorns. And that, my darlings, is how little Palo Verdes are born.

This specimen planted in front of the Mesa Air Museum is variously known as a Littleleaf Palo Verde, Yellow Palo Verde, or Foothill Palo Verde. The seeds are edible. Dry ones can be ground up for flour; green pods went into Native American stews, and green seeds were merely munched. Remember this if you’re ever stuck out in the Sonoran Desert with no food.

Next, I’ll tell you where to get water.

Saguaro (Carnegiea gigantea)

Hey, guess what Arizona’s state flower is? It’s a bloomin’ cactus! Saguaros have great big white blooms that perch atop those gigantic arms like a too-small hat. Unfortunately, they were pretty much done flowering when we got to Arizona, so all you get is cactus.

These are interesting buggers. They’re picky – they only grow in southern Arizona, a teesny bit of California, and Sonora, Mexico. Most of the ones in this photo are old – those characteristic arms sometimes don’t develop until the plant’s reached its 75th birthday. They could live to twice that age.

They’re gluttons for water, living in the desert as they do. They’re veritible storage tanks. When it rains, they suck up as much moisture as they can hold, storing it against dry days. When it rains a lot, they may suck up so much water they burst. And no, you wouldn’t want to be standing next to one when it happens.

The blooms give way to a dark red fruit that’s delicious if you can get your hands on it.

They’re pollinated by bats, believe it or not. Their primary pollinator, in fact, has the delightful name of the Lesser Long-Nosed Bat. Saguaros also play apartment house to a variety of birds. As you can imagine, the main constructors are woodpeckers, who excavate holes in the trunks. How does that happen, what with all the spines, you ask? Well, those spines are in neat rows spaced widely apart, which allows plenty of room for housing development. If you’re really lucky, you might see an Elf Owl peering out at you from his saguaro house.

Speaking of houses, the thick ribs of the saguaro can be used as building materials – check out the roofing on San Xavier del Bac’s cloisters sometime, and you’ll see how that works. Of course, the cacti are now protected, so don’t ask for a saguaro-rib roof yourself.

Now you’ve had a meal and a drink – how about some soap to wash up with?

Yucca (Yucca elata)

I know, soap’s not the first thing that comes to mind when you look at this spiky plant, is it? But this is a soaptree yucca, and you can indeed extract a soap-like substance full of saponins from their roots and trunks – if you feel like braving narrow leaves with hard, sharp points. Like most desert denizens, they’ve perfected the art of the spike. It’s rather easier to peel yourself off one of the fibers that curl back from the edges of the leaves so you can floss your teeth than it is getting to the soap, but if you have dandruff, it might be worth some extra effort.

This one, photographed near Benson, Arizona, is in riotous bloom, which is likely making the yucca moths happy. Yucca moths have an exclusive contract with yuccas – they pollinate, and in return, get to lay their eggs deep in the flower, where they’re protected by the fat oval seed pods that develop. The moth larvae get to eat a seed or two, which seeds were made possible by the yucca moth’s mom, and everybody’s happy.

You’ll find the soaptree yucca ranging throughout southern and central Arizona, west Texas and New Mexico. You might even find a few in Europe – they’re cold-hardy, just so long as they get plenty of sun.

The Tohono O’odham use the soaptree yucca as a major source of their basketry fibers. So there you go: soap, floss, and baskets all in one go. Useful little bugger, innit?

All yuccas are part of the agave family, which means they’re also related to my favorite drink: tequila. The Mohave yucca provided the original root in root beer, and its stems are used for livestock deodorant. This family may be spiky, but boring they are not.

Those are only three of the thousands of the botanical denizens of the Sonoran Desert. Since we didn’t spend a lot of time there, I haven’t got many pictures, but you can explore on your own. Pay special attention to the ocotillo, which shall feature in a future Sunday Sensational Science.

We’re headed to central Arizona next, which is a transition zone in more than one way. You’ll find our old friends the Palo Verdes there, as well as the ubiquitous agave. You’ll also begin to learn why Arizonans consider cacti weeds.

Century Plant (Agave palmeri)

Another member of the agave family blooms just once. These two Palmer’s agave by Jerome, AZ are at the end of their lives: they’re monocarpic, meaning that after they bloom, fruit and seed, they die. Lucky for them, their seeds, contained in fruits called pups, are really good at germinating.

Despite being called “century plants” or “century trees,” they only live for 5-25 years. In their last year of life, they shoot up a stalk that can grow by an astonishing foot a day, up to 20 feet in total, and throw out their beautiful blooms. They’re sampled by a huge variety of critters, everything from insects to hummingbirds to our old friend the Lesser Long-Nosed Bat. Both they and the Mexican Long Tongued Bat use Palmer’s agave as a refueling station during their migrations from Mexico to the Sonoran Desert. This works well for the plants, because they rely on the bats for pollination. Everybody else is pretty much just a freeloader.

Their leaves contain wonderful fibers that natives used for making hunting nets, baskets, and sandals.

And yes, you can make mescal from these agave. But since they’re threatened by loss of habitat, we’d much appreciate it if you didn’t.

These gorgeous plants grow in great swathes in the 3,000 to 6,000 ft elevation in Arizona and Mexico. Watch out for them hiking. Those long leaves don’t just funnel water down to the stem of the plant, they’re tipped with strong spikes that can do some pretty awesome damage if you ram yourself on one. Those leaves also have smaller spines that make the sides of the leaf feel like saw teeth. If you’re careful, though, you can go feel the plant’s air conditioning system – they have a waxy coating with a powdery surface that both seals in water and deflects up to 3/4 of the sun’s heat. While you’re sweating miserably in the mid-summer heat, they’re hanging out all cool and moist inside.

Prickly Pear (Opuntia engelmannii)

Chances are, prickly pear cacti are no strangers to you. One species, Opuntia ficus-indica, is probably hanging about in your produce aisle right now, since it’s a food crop. Prickly pear come in a bewildering variety made all the more bewildering by their profligate hybridizing. And they’ve pretty much taken over the world. My Australian readers have probably had cause to curse them at some point – there, they’re an invasive species.

Here, we loves ’em. Opuntia engelmannii pops up nearly everywhere. Catch him at the right time, and you’ll get treated to either spectacular blooms or lush reddish-purple fruit. Better gather your prickly pear buds while ye may, though – each bloom lasts for only a single day.

They’ve got a connection to Charles Darwin, too – he “was the first to note that these cacti have thigmotactic anthers: when the anthers are touched, they curl over, depositing their pollen. This movement can be seen by gently poking the anthers of an open Opuntia flower.” But you’d best poke very carefully – the long spines are easy to avoid, but they’re surrounded by hair-fine glochids, which are nasty little spines that will cause you misery if you get them embedded in your skin. I know this from bitter experience.

Arizona’s prickly pear have pads that face mostly east-west, proper little solar panels that maximize their sun exposure during the summer rains. Those pads contain a moist pith filled with sap. It feels like glue and tastes like that white craft paste we used in elementary school, but if you’re desperate in the desert, it’s great stuff.

What’s that you say? You’re sick of cacti? You want to drink real water, not cactus juice? But I was about to tell you about all our lovely Ferocactus wislizeni barrel cacti, whose heads you can lop off and find tanks of water stored inside! Okay, granted, it’s water tainted with oxalic acid and can give you the runs, but still, better diarrhea than death, right?

Fine. We’ll head for some riparian areas, then. You can take your chances with Montezuma’s Revenge, and then hang about in the lovely cool shade.

Arizona Sycamore (Platanus wrightii)

If you hang about the creeks and rivers of central Arizona, New Mexico and Mexico, you’re likely to run into groves of these gorgeous trees. They not only look pretty, they smell good – that fresh, sweet, green smell that just screams water, shade and contentment. That is, until one of their spiky seed balls bops you on the head. That’s the female bloom’s doing – the male’s is more like a marble. These sycamores are hermaphrodites, so expect both genders.

They’re water-loving trees who grow best when the water table’s not too low, so don’t expect to see them out on the open plain. They cling to areas with at least intermittent water flow, where they drink efficiently from moist soils and grow big – up to 65 feet, sometimes 80 if they’re really excited. They typically extend one big limb out over their water source. This, I can tell you, is an excellent idea, and was practically tailor-made for those who want to sit over the creek on a hot Arizona summer day.

Those lovely spreading crowns with their wide, long-lobed leaves provide a lot of cool, green shade. The bark is mottled gray and white, baby-smooth and wonderfully cool to the touch. Which is what your author did, repeatedly, on her visit to Montezuma’s Castle. Have you hugged your tree today?

These trees are pretty safe from commercial exploitation. They don’t produce tasty fruit, and their wood is virtually useless – too hard to work with. About the only thing you can make of it is buttons and butcher’s blocks. It’s highly resistant to splitting, which makes it ideal for those purposes. But we’d rather leave it standing, as it’s a sovereign remedy against stream bank erosion. Believe me when I say Arizona stream banks need all the help they can get.

As the trees get old, their bark gets more gnarled, and they can hollow out, providing a happy home to woodpeckers and other birds.

Venus Hair Fern (Adiantum capillus-veneris)

Sometimes when you travel, it’s nice to see something familiar. If you’re from Africa, Asia, Europe, or North America, you’ve probably seen a Venus Hair fern. You might even have one growing in a garden, or keep one as a potted plant.

In the wild in North America, they especially like south-facing, sheltered limestone walls, such as this one. You might find them growing around foundations or in the mortar around storm drains, although that’s pretty bloody unlikely in a place as hot and dry as Arizona. They’re not all that fond of the dry.

The natives might have used them for medicine – they’ve been widely used in folk medicine for an astonishing variety of ailments. However, none of their properties are clinically proven, and they may not be especially healthy to ingest. Best just to sit on the stream bank and enjoy their fronds trailing happily in the water.

Suitably soaked? Then let’s head for the hills again.

Silverleaf Nightshade (Solanum elaeagnifolium)

As you might have guessed from the name, this gorgeous little purple flower is a wee touch deadly – at least to livestock. It’s the bane of anyone trying to get rid of it, since it can regenerate from just a fragment of its roots. But for those of us who like wildflowers and have no cattle to worry about, it’s a delight.

The silvery sheen on its leaves comes from downy hairs. It’s a tough little bugger, able to withstand crappy soil with very little water. This one’s growing at Gold King Mine in Jerome, AZ, not exactly a friendly place for flora.

The plant does have its uses for humans. It puts out little red, yellow or orange berries that the Pima used as vegetable rennet (one presumes for making cheese). The Kiowa used the seeds along with brains for tanning hides.

No one’s quite sure whether the plant’s native to North America and got accidentally introduced to South America, or if it was the other way around. Whichever is the case, it happily grows in both places today.

Well, my darlings, we’ve made it to Central Arizona, and I think we’ve had quite enough botany for one Sunday. We’ll spend the night in Sedona, and then head on up to Flagstaff next week. If you’re pining for more botany, you can amuse yourselves by seeing how many native plants you can identify in this photo:

You can also try to catch me in any errors. I did my best to be as accurate as possible, but I’m no botanist and plants in the wild don’t carry labels, so some of my identifications may be slightly off as to exact species or subspecies. If you’re an expert in Arizona flora, feel free to set me straight in comments. Just know that if you question my identification of the saguaro, I’ll know you’re having me on.