The Champlain Thrust is a 200-mile long fault extending from southern

Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...

, down through western

Vermont Vermont () is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, New Hampshire to the east, New York (state), New York to the west, and the Provinces and territories of Ca ...

in the

Champlain Valley The Champlain Valley is a region of the United States around Lake Champlain in Vermont and New York extending north slightly into Quebec, Canada. It is part of the St. Lawrence River drainage basin, drained northward by the Richelieu River into ...

, and into eastern

New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...

in the

Catskills The Catskill Mountains, also known as the Catskills, are a physiographic province and subrange of the larger Appalachian Mountains, located in southeastern New York. As a cultural and geographic region, the Catskills are generally defined a ...

Hudson Valley The Hudson Valley or Hudson River Valley comprises the valley of the Hudson River and its adjacent communities in the U.S. state of New York (state), New York. The region stretches from the Capital District (New York), Capital District includi ...

. This east dipping

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. I ...

transports

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

passive margin shelf rocks westward by about and places them on top of

Middle Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era, and the second of twelve periods of the Phanerozoic Eon. The Ordovician spans 41.6 million years from the end of the Cambrian Period Ma (milli ...

rocks. The Middle Ordovician accretion of the one or more island arcs terranes drove the initial thrusting during the

Taconic Orogeny The Taconic orogeny was a mountain building period that ended 440 million years ago (Ma) and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the east coast of the ...

, though reactivation of the fault may have occurred during the middle Devonian

Acadian Orogeny The Acadian orogeny is a long-lasting mountain building event which began in the Middle Devonian, reaching a climax in the Late Devonian. It was active for approximately 50 million years, beginning roughly around 375 million years ago (Ma), wi ...

.Rolf Stanley, The Champlain thrust fault, Lone Rock Point, Burlington, Vermont., Geological Society of America Centennial Field Guide--Northeast Section, 1987 The Champlain Thrust marks the most westerly thrust of the Taconic Orogeny.

Prominent exposures

The thrust fault is exposed to the north of the city of

Burlington, Vermont Burlington, officially the City of Burlington, is the List of municipalities in Vermont, most populous city in the U.S. state of Vermont and the county seat, seat of Chittenden County, Vermont, Chittenden County. It is located south of the Can ...

on the shores of

Lake Champlain Lake Champlain ( ; , ) is a natural freshwater lake in North America. It mostly lies between the U.S. states of New York (state), New York and Vermont, but also extends north into the Canadian province of Quebec. The cities of Burlington, Ve ...

at Lone Rock Point. Here the

Lower Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovici ...

Dunham Dolomite can be seen thrust on top of the Middle Ordovician Iberville shales.

References

External links

Vermont State Geologic Survey Website

Geology of Vermont Structural geology {{struct-geology-stub