This is Pinacate!

World Heritage Site -- Biosphere reserve
Geologic wonder in the heart of the Sonoran Desert
Ongoing site revision 2014

This striking dawn image from the International Space Station shows Pinacate’s scattered cones, huge calderas, and volcanic mountain surrounded by the sand dunes of the Gran Desierto de Altar and the crystalline mountains of the Gila-Pinacate Borderland. Pinacate is a “monogenetic volcanic field,” the most common kind of Quaternary volcanism on earth. The cones are monogenetic, each is the product of a single, short eruption of a unique batch of magma that produced less (usually much less) than a tenth cubic km of rock. Fifty similar fields within a thousand kilometers have their unique basalt magma batches nearly identical because that’s how partial melting of the mantle works. The mountain, a trachyte shield volcano, is different from the cones in many ways but its magmas also came from the mantle. Pinacate has 465 identified eruptive centers, only a few in the north (diagonally toward the upper right) are cut out of this image.

This is Dan Lynch’s Pinacate book, an attempt to tell the geologic story mainly through photographs and their captions without the reams of text of a paper book. I have tried to layer this site appropriately for everybody; geologists, volcano lovers, Pinacate people, and the idly curious. Those of you who are returning from a previous visit recognize a new index page designed to link to lots of pictures. The old index page, now called "geology," remains the gateway to the scientific website. Major alterations will come with many more new images and pages. The menu will be changing as I write new stuff and those updates are posted on the changes page which is accessible from the rightmost button showing the last upload of the page you are on. This site uses Fancybox (Janis Skarnelis) that scales images to fit your screen. Most images are 1200 px wide or 900 px high and can be enlarged to see detail using the double diagonal arrow in the icon at the page top. Visit about for more information about the site. PLEASE - send me an e-mail and tell me how to improve it.

Forty years of loving Pinacate.

Many of these images are scans of 35mm transparencies from a collection that started in 1972. No attempt is made to tell a story here, they're just pictures. I will be adding more as time goes along.

STEREO!

This is worth doing, there’s a wealth of information in the third dimension. Try it! You'll like it! It may be difficult at first but you will be astounded by how much more there is to see in 3-d. These are all cross-eye stereos having the right image on the left, etc. Hold your head on a line perpendicular to your monitor with your eyes parallel to the horizontal center line of the images. Cross your eyes to make a third (blurry) image between the others and when things come together, your eyes will focus and you'll see sharp stereo. You will probably have to twist your head to align the images. The more you do it, the easier it gets.

Write me about your experience with these stereos.