MARBLE MOUNTAINS
The southern end of the Marble Mountains, in southern
California's Mojave Desert, is famous for its abundance of fossil
trilobites. On some maps, this area is called the “Trilobite Wilderness”.
The rocks here are Lower Cambrian. The best known fossiliferous unit is
the Latham Shale (Dyeran Stage, upper Lower Cambrian). The
scree-covered slope in the middle of the stratigraphy shown below is the
Latham. The unit underlying the Latham is the Zabriskie Quartzite, a
well-cemented quartzose sandstone. Above the Latham is the Chambless
Limestone, which is dominated by oncolitic limestones containing fairly large Girvanella
oncolites.
The Latham contains common olenelloid trilobites (disarticulated sclerites & complete specimens). It has also produced soft-bodied fossils, though not in the abundance or quality of Canada's Burgess Shale or China's Chengjiang deposit. Described & undescribed soft-bodied fossils from the Latham Lagerstätte include anomalocarids, eldonioids, palaeoscolecidan worms, algae/bacteria, etc. Known shelly fossils include brachiopods, hyoliths, polymeroid trilobites (~two dozen species), and eocrinoids. The Latham also has cnidarian & vermiform trace fossils and coprolites.