Geology and Mineral Resources

Champlain Valley from the summit of Mt. Philo, Charlotte, VT


View west towards the Adirondack Mtns.	View south towards Snake Mtn.; hills are the upper plate of the Champlain Thrust.

Click for a Bedrock Geologic Map of Mt. Philo, 2009 ; Click here for the Bedrock Geologic Map of Charlotte, 2009; Click here for the glacial geology and hydrogeology of Charlotte.

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.