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Trimble Knob, located southwest of Monterey in Highland County, Virginia, is a conical hill composed of basalt, a volcanic rock, of Eocene (early Tertiary) age.It is the eroded remnant of what was an active volcano or diatreme that last erupted approximately 35 million years ago, making it one of the youngest volcanos on the east coast of North America.
The basalt at Mole Hill (and other igneous dikes in the area) was originally thought to be of Paleozoic age by relative age dating using cross-cutting relationships. [1] In 1969, Fullagar and Bottino used K-Ar and Rb-Sr radiometric dating techniques to date rocks that they thought were temporally related to the Devonian Tioga Bentonite, but discovered that the rocks were actually a much ...
The volcano is composed of alkali feldspar granitic rock of the Robertson River Igneous Suite.This includes felsic complex material such as biotite, hornblende-biotite, magnetite, and alkali granitic rock including rhyolite on the eastern slopes of Battle Mountain [5] and the adjacent (and geologically related) Little Battle Mountain (elevation 937 feet).
Pages in category "Volcanoes of Virginia" The following 5 pages are in this category, out of 5 total. This list may not reflect recent changes. B.
The USGS also operates five volcano observatories throughout the nation: the Alaska Volcano Observatory in Anchorage, Alaska (on the campus of Alaska Pacific University), the California Volcano Observatory in Menlo Park, California, the Cascades Volcano Observatory (covering volcanoes in Idaho, Oregon, and Washington) in Vancouver, Washington ...
Mountains of Warren County, Virginia (5 P) This page was last edited on 20 February 2022, at 22:00 (UTC). Text is available under the Creative Commons ...
The Mount Rogers area contains a unique record of the geohistory of Virginia. There is evidence from the rocks that volcanoes were part of the landscape. Roughly 760 million years ago, rift-related (divergent) volcanoes erupted along the axis of what later became the Appalachians, and one remnant of that volcanic zone, with its volcanic rocks, still can be seen at Mount Rogers.
The geology of Virginia began to form at least 1.8 billion years ago. The oldest rocks in the state were metamorphosed during the Grenville orogeny , a mountain-building event beginning 1.2 billion years ago in the Proterozoic , which obscured older rocks.