Not too long ago, I visited the San Pedro Mountains, which contain the oldest rocks exposed in the Jemez region. You can visit that post for a more detailed explanation of the geology of this area, but the short version is that the San Pedro mountains are a block of...Read more

This unit has interested me since I first learned about it, and I’ve visited it once before. Basanite is a somewhat rare and unusual igneous rock type, very low in silica and somewhat enriched in alkali metals. The Cieneguilla Basanite is the only basanite identified so far in the Jemez...Read more

For some time, Gary Stradling has wanted to find some good chunks of obsidian on which to practice his knapping skills. (Not to be confused with “napping”, at which we are both already skilled.) Raw obsidian suitable for toolmaking must of course come in chunks large enough to work with,...Read more

320 million years ago, New Mexico was a shallow tropical sea studded with large islands. These were the peaks of the Ancestral Rocky Mountains, formed when Africa collided with North America and compressed the Earth’s crust in the New Mexico area. Blocks of crust were forced upwards by the compression...Read more

My first crack at this trail ended badly when I realized my camera wasn’t focusing properly. Repairs were not entirely successful and I ended up with a new camera. A subsequent attempt ran out of time. This time I had the whole afternoon, a working camera, and flawless weather. But...Read more

I’ve been to the Harding Mine three times before. The first was as a middle-school kid, for a science field trip, which is one of the great happy memories of my childhood. I still have some good specimens from that trip. The second was around nine years ago, with Bruce...Read more

It’s been a while since I spent some serious time hiking in the Sierra de los Valles, the range of mountains west of Los Alamos that is also the east rim of the Valles caldera. This is not an area to hike during thunderstorm season, but the forecast was for...Read more

If you look at my map of where I’ve been, you see a number of blank areas. One I’ve been thinking about for a while is the San Pedro Mountains, the northwesternmost corner of the Jemez Mountains. I’ve not visited it much because it’s the farthest corner from home and...Read more

I’ve explored the Pajarito Trail north of Rendija Canyon a couple of times before. However, I was looking for a not too long hike today, the weather was absolutely cloudless, I have not actually hiked to the top of Guaje Mountain before, and it seemed like a perfect day to...Read more

This weekend I joined other members of the Los Alamos Geological Society on a field trip to the Small Fry prospect on the highway to El Rito (“The Ritual.”) Here the amateur geologist can find interesting samples of fluorite, calcite, and barite. A prospect is a location on public lands...Read more