Why is Lake Champlain long and narrow?

December 1, 2009

Lake Champlain and the Hudson River are part of an old rift valley that formed when the Atlantic Ocean started to open, about 200 million years ago.  As mantle convection currents began to pull the supercontinent Pangea apart, the Earth’s crust in this region came under tension and several cracks formed. The Connecticut River valley and the Penobscot River valley are also failed cracks from this time. One of the cracks continued opening and filled with what we now call the Atlantic Ocean. Later, during the period 100,000 to 20,000 years ago, the Lake Champlain Basin was sculpted by successive ice sheets. But the Lake Champlain Basin was not scooped out by the ice sheets.

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What is the age of Lake Champlain shale and limestone found in the Champlain Thrust Fault?

December 1, 2009

The limestone, called Dunham Dolomite, formed in the Cambrian geologic period, about 500 million years ago.  The younger Iberville Shale formed in the Ordovician period, about 450 million years ago.  During the formation of the Green Mountains, about 350 million years ago, the Champlain Thrust Fault formed, which pushed the older dolomite up on top of the younger shale. The Champlain Thrust fault can be seen from Lake Champlain at Lone Rock Point in Burlington. Visit the link below for some images and more details.


Are the Adirondack mountains growing?

December 1, 2009

Yes, there is a “hot spot” in the mantle underneath the Adirondacks.  The uplifting is estimated  at about 1mm – 3mm per year.  Some geologists believe that the erosion is outpacing the uplift, however.


Lake Champlain and Basin Facts

September 28, 2009

Here are the basic facts on the Lake from the Lake Champlain Basin Atlas!

Lake Length: 120 miles (193 kilometers). Lake Champlain flows from Whitehall, New York north almost across the U.S./Canadian border to its outlet at the Richelieu River in Quebec. From there, the water joins the St. Lawrence River, which eventually drains into the Atlantic Ocean at the Gulf of St. Lawrence.

Greatest Width: 12 miles (19 km).

Greatest Lake Depth: 400 ft. (122 meters). The waters of Lake Champlain reach their greatest depth in the area between Charlotte, Vermont and Essex, New York. Visit the Lake Depths page in the Lake Champlain Basin Atlas for more information.

Average Lake Depth: 64 ft. (19.5 meters).

Average Annual Water Level: 95.5 ft. Normal annual variation between high and low average water levels is about six feet (2 meters) in Lake Champlain, but since the early 1870s when daily records began, the maximum range between the high and low average water levels was measured at 9.4 feet (3 meters).

Record High Water Level: 101.89 ft. recorded in 1993 at Rouse’s Point.

Record Low Water Level: 92.4 ft. recorded in 1908.

Lake Area: 435 sq. miles (1127 sq. kilometers) of surface water.

Average Volume of Water: 6.8 quadrillion gallons (25.8 trillion cubic meters).

Water Retention Time: Varies by Lake segment. It is longest in the Main Lake, about three years and shortest in the South Lake — less than two months.

Amount of Shoreline: 587 miles (945 kilometers) of shoreline.

Number of Beaches: There are about 54 public or commercial beaches and 10 private beaches on the Lake’s shores. Visit the Beaches page in the Lake Champlain Basin Atlas for more information.

great blue heron

Average Lake Freeze Date: The average Lake freeze date (across the Lake’s widest part) is February 12th. During the frigid winter of 2003, it froze on February 15th, and during 2004, the Lake froze on January 27th. In 2005, it froze on March 8th. However, the Lake is still freezing less frequently across its widest part than it has in the past. Visit the National Weather Service for recent years.

Lake Segments: The Lake is divided into five distinct areas, each with different physical and chemical characteristics and water quality. These lake segments include: the South Lake, the Main Lake (or Broad Lake), Malletts Bay, the Inland Sea (or Northeast Arm), and Missisquoi Bay.

Lake Stratification: Lake Champlain stratifies in the spring and summer. The warmer, less dense, upper layer (epilimnion) of the Lake typically extends down about 33 feet (10 meters) in the Main Lake during the summer. Below this layer, there is a sharp transition in temperature called the “metalimnion” or “thermocline,” to the much colder waters below, called the “hypolimnion”.

Number of Islands in Lake: More than 70.

Area of the Basin: 8,234 sq. miles (21,326 sq. kms). Ninety percent of the water that enters Lake Champlain flows through the Lake’s drainage basin before it reaches the Lake.

Land Distribution: Fifty-six percent of the Basin is in Vermont, 37% is in New York, and 7% is in the Province of Quebec.

Area of Wetlands in the Basin: More than 300,000 acres. Visit the Wetlands page in the Lake Champlain Basin Atlas for more information.

Average Annual Precipitation: More than 50 in. (127 cm) in the mountains and 30 in. (76 centimeters) near the Lake or in valleys. Visit the Climate page in the Lake Champlain Basin Atlas for more information.

Growing Season: 150 days near the Lake and 105 days in higher terrain.

Average Annual Air Temperature: 40-45 degrees Fahrenheit (4.4-7.2 Celsius).

Population of Basin: 571,000 (541,000 in the US according to the 2000 Census Data, and 30,000 in Quebec). About 68% live in Vermont, 27% in New York, and 5% in Quebec. Density is about 61 people per sq. mi. Visit the Population page in the Lake Champlain Basin Atlas for more information.

Drinking Water Use: Approximately 200,000 people or about 35% of the Basin population, depend on Lake Champlain for drinking water. Approximately 4,149 draw water directly from Lake Champlain for individual use. There are 99 public water systems drawing water from Lake Champlain.

Tourism Expenditures: About 3.8 billion in 1998-99. Visit the Economics in the Lake Champlain Basin Atlas page for more information.


Is Lake Champlain’s deepest point is farther below sea level than any other point in the U.S.?

September 22, 2009

No.  At about 400 feet deep, Lake Champlain’s deepest point is below the elevation of Death Valley (the lowest surface point in the U.S.), but Lake Superior’s deepest point is a couple of hundred feet farther below sea level than Lake Champlain’s deepest point.  Lake Superior’s deepest point is on the U.S. side of the U.S.-Canadian border.

Death Valley’s elevation:                    282 ft. below sea level

Lake Champlain’s deepest point:        304 ft. below sea level

Lake Superior’s deepest point:           725 ft. below sea level


Do the Adirondacks have high-quality granite that is quarried?

July 23, 2009

Although there are a few granite quarries in the Adirondacks, the majority of Adirondack rock is metamorphic. Granite is a plutonic igneous rock, meaning it solidifies from molten rock within the earth, but without being subjected to additional heat and pressure.  If more granite existed in the Adirondacks in the past, it has long since been metamorphosed by the intense heat and pressure the region has been subjected to.  When metamorphosed, granite transforms into a rock called gneiss, which is not a good building stone.  The rocks of the Adirondacks are geologically much older than the Green Mountains (over one billion years old vs. 400-500 million years old).

http://nygeosurvey.geology-forum.com/

http://gretchen.geo.rpi.edu/roecker/nys/adir_txt.html


Where is the world’s oldest fossil reef? Is it world’s oldest coral reef?

July 23, 2009

While some references state that the world’s oldest coral reef is in Isle La Motte, VT, the Chazy Reef on Isle La Motte is more accurately the world’s oldest fossil reef.

Formed by the Iapetus Ocean, the fossil and rock formation is the oldest reef in which corals appear.  Most of the reef was formed by stromatoporoids, a type of reef-forming sponge.  The best places to see the old fossils in this formation are the Goodsell Ridge Preserve and the old Fisk Quarry – both in Isle La Motte, Vermont. 

http://www.lclt.org/GoodsellUpdate.htm

http://www.lcbp.org/wayside/sites/chazyreef.htm

http://www.lcbp.org/Atlas/HTML/nat_geology.htm

http://www.anr.state.vt.us/dec/geo/chazytxt.htm