|
|
|
|
|
Geology
of Vermont
Champlain Valley from the summit
of Mt. Philo, Charlotte, VT
Photograph & text, M. Gale, 1999
Click for the Bedrock Geologic Map of Mt. Philo, 2009
The views of the Champlain
Valley from the top of Mt Philo (elev. 968 ft) are exceptional. Much
of the landscape has developed due to both erosion and deposition
by glacial ice and meltwater. Vermont was heavily glaciated and once
buried beneath ice. The glaciers carved away rock and ground it into
finer grained sands and gravels, scoured valleys, and left behind
rounded bedrock with grooves and striations. As the glaciers melted
and retreated 12,000 years ago, ice dams and melting water formed
lakes. Running water and melting ice deposited eroded material as
deltas and moraines. The materials deposited at the surface help explain
the history and evolution of the landscape. As the glaciers retreated
from Vermont, Mt. Philo was an island in an inland sea as evidenced
by the marine sand deposits at its base. The State Fossil, the Charlotte
Whale, is believed to have died in a shallow marsh of the Champlain
Sea and been covered by fine clay sediment, providing more evidence
for changes in climate and history of the Lake Champlain area. Yet
all this activity is recent when compared with the 550 million year
old bedrock of the Champlain Valley.
The Cambrian andOrdovican sedimentary rocks
of the Champlain Valley formed from sediment (sand, silt, carbonates
and shells) deposited in shallow water along the continental margin
in the Iapetus Ocean, a precursor to the Atlantic Ocean. The rock
at the summit of Mt. Philo, also at Redstone Natural Area, is Monkton
Quartzite. The oldest rocks are usually at the bottom of a deposit,
but at Mt. Philo, the rocks at the summit are older than the rocks
in the valley. The rocks moved up through the geologic section along
faults.
|
Geology and Mineral Resources Division 
dec calendar 
