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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 ...
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 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).
Name Elevation Location Last eruption meters feet Coordinates; Malumalu: Last 8,000 years Ta‘u-931: 3054: 30,000 years ago [15]: Ofu-Olosega: 639: 2096: 1866 unnamed submarine cone eruption
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.
The building in which the museum is located was originally built as a weather station in 1909 after the federal government bought a 150 square foot plot of land from the city. The U.S. Weather Bureau maintained records of local conditions and tracked extreme weather events at the station from February, 1910 to June, 1953.