(Originally published in 2007, Updated 2017)
We finally made it to the "local" trilobite site! We'd tried last summer, but not knowing exactly where we were going, we encountered too many sharp rocks for our little Accord. But this time we were prepared. 🙂 With verified GPS coordinates, a Google Earth fly-by terrain map, and my newly acquired Tacoma PreRunner, we charged right along.
The site is located roughly in the Barstow area, in the foothills just northeast of Amboy, CA -- a ghost town on old Route 66. The best road marker to the site is Chambless. Heading east on 66 past Roy's Diner, there will be a road to the right going to Cadiz. The vacant store at that corner is what's left of Chambless. The store marks the best spot to turn LEFT towards the mountains. Simply veer off the road at a convenient "off ramp" and follow paths that will take you most directly north.
You can actually see the site from the road. Looking at the four ridges to the north, it's at the eastern base of the second-to-last ridge, and it looks like a band of dark brown stripes, slanting down to the right. That is the famously fossiliferous Latham Shale layer, home to many of the earliest creatures, who swam the tropical north shore of the land-mass-that-would-become-known-as-North-America some 570 million years later.
As long as you stay on the correct dirt-and-gravel path, the parking spot (at the base of the 4th peak) will be easy to find. A family car can do the drive, as a precaution, I'd still recommend 4WD or at least a vehicle with good clearance, along with a good spare tire. The parking space is separated from the site by a small ravine. One can avoid the ravine by going around the bottom, but it's a much longer walk than the more direct route "up-and-over". The direct route is steeper, and it requires some scrambling.
You know you're at the quarry when you find an area, going up the side, with nothing but lots of broken pink and green shale pieces. The Latham Shale layer is a narrow track sandwiched between brown cliffs. You get at the fossils by prying or hammering away layers of shale from the mountainside and then splitting them with a chisel or rock hammer, inspecting each exposed side for treasures. It's typical after about 20 minutes on average to find a head shield of a trilobite, the same color as the rock, but molded very cleanly. Trilobite bodies at this site are rare, however, because the Ollenids were such an early species that their body armor wasn't sophisticated enough to withstand fossilization, except by luck. Not to mention that as the first creatures to evolve multiple body parts, they also fell apart easily! Besides trilobites, there are other fossils to be found, including a few other plantlike creatures and a "monster" of a creature, the anomalocaris, which resembled a 2 foot long shrimp.
In all, we spent about 2-1/2 hours hammering at shale, and the two of us found about 15 trilobite fossils, and we kept a few. Since it's a weekend outing for us, we figure to go many more times and try looking for some other fossils, too. 🙂
If you ever decide to make the trip, be sure to check out this site that has a pretty thorough description of the entire ordeal. The only warning I would change is that as of now, Roy's is not a functioning motel or eatery, but they do have gas and drinks. The nearest motel is in Ludlow, which is a truck stop town where Route 66 splits from 40. I recommend reservations, but unfortunately, I don't remember the name of the place.
In February, I had a quick visit with my girlfriend to the fossil site. We only were able to get in about 1/2 hour of digging before cloud cover gave us a premature sunset.
Nevertheless, I was able to make some great finds just in the first 10 minutes, including several pieces containing multiple trilobite fossils!
A hint I'll give you is to walk up the slope along the left-hand side and look for others' discards among the larger shale pieces and atop boulders. That will give you a quick start with a preview of what you're looking for. In fact you could easily make an entire day of sorting through rubble without splitting any rocks -- if you wanted, anyway... it's definitely fun to break open a rock, as if opening a book to page 374, and see a 500 million year-old bug looking up at you!
I also learned a better way to access the site using slightly more drivable dirt-and-gravel roads. I got these directions from a PDF you can download called Mojave-Mecca Geology Field Trip Guide Book that includes the text directions. Using these directions, your drive will be considerably flatter, with less worry of encountering sharp rocks.
As For The Other Cadiz Rd Trilobite Site...
I also visited the Latham Shale site in 2010 along with other well-known trilobite quarry to the south along Cadiz Road. Most unfortunately, I discovered that the entire site had been stolen! It was literally mined out in its entirety with a steam shovel. I was however able to dig through leftover rubble and find a nice specimen, probably one of the last remaining at that historically-fruitful site.
So now all that's left in that area for casual collectors is the Latham Shale site. Fortunately, there's really no sign that it'll be mined out, so long as everyone is respectful and takes home only one or two of your favorite pieces.