Trilobite Point
From Wikipedia, the free encyclopedia
| Trilobite Point | |
|---|---|
 Trilobite Point (right of Mount Holmes) from Madison River | |
| Highest point | |
| Elevation | 10,010 ft (3,050 m) |
| Coordinates | 44°49′01″N 110°50′38″W / 44.81694°N 110.84389°W[1] |
| Geography | |
 | |
| Location | Yellowstone National Park, Park County, Montana |
| Parent range | Gallatin Range |
Trilobite Point is a mountain peak in the southern section of the Gallatin Range in Yellowstone National Park. It has an elevation of 10,010 feet (3,050 m). In 1883, William Henry Holmes of the Hayden expedition named it after trilobite-bearing exposures of Cambrian sedimentary strata that he found just below its summit and around it.[2]
The summit of Trilobite Point consists of an erosional outlier of the unfossiliferous cherty dolomites of the Ordovician Bighorn Dolomite. Underlying the Bighorn Dolomite and exposed in steep slopes, from youngest to oldest, are the Cambrian limestones, dolomites, shales, and sandstones of the Snowy Range Formation, Pilgrim Limestone, Park Shale, Meagher Formation, Wolsey Shale, and Flathead Sandstone. The Flathead Sandstone is underlain by Precambrian metamorphic rocks. These strata are intruded by two, thin rhyodacite porphyry sills. A third, thicker rhyodacite porphyry sill separates the Flathead Sandstone from the underlying gneissic metamorphic rocks.[3]
Fossils
.jpg)
The most fossiliferous of these geologic formations is the Pilgrim Limestone. Abundant trilobite fragments have been observed, often as a fossil hash, as discrete beds in its lower and middle parts. Within Yellowstone National Park, the Pilgrim Limestone has yielded fossils of the enigmatic Chancelloria, hyoliths, brachiopods, trilobites, and conodonts. One of Walcott’s[4] trilobites, Solenopleura? weedi, is now attributed to the Pilgrim Limestone. Cambrian sponge spicules, hyoliths, brachiopods, trilobites, crinoid fragment, and invertebrate trace fossils have been collected from 11 outcrops within the vicinity of Trilobite Point.[5][6]
