An Outdoor Geology Museum

An Outdoor Geology Museum. Shaped by Rock, Water, and Ice. , Great Lakes Seaway Trail bedrock and surficial geology form a foundation for scenic spectacles, A TRAIL OF DRAMATIC LANDSCAPES , The Great Lakes Seaway Trail crosses a wide variety of spectacular landscape features made of bedrock, glacial debris, and water. Most of the bedrock originated as maritime sediments deposited in ancient oceans and turned into rock by compaction; some bedrock was formed when molten rock from deep within the earth came near the surface and cooled. The bedrock is covered in most stretches of the Trail by glacial features. Abundant water resources along the Trail shaped and were shaped by the rock and glacial deposits. This rocky legacy has created an outdoor museum by the work of geologic agents., GLACIATION , During the Ice Ages, the Great Lakes Seaway Trail was alternately covered and uncovered by ice up to 2 miles thick. As the last ice sheet advanced southward, it bulldozed previously deposited soils, gravels, and boulders, scraping to bare bedrock in places (barrens), leaving huge boulders (glacial erratics), and forming mounds of rock and soil debris (drumlins and moraines). As the ice melted about 10,000 years ago, huge temporary lakes were formed and raging rivers cut deep gorges. These massive forces are responsible for the unique landscape features seen today., [Notable natural features along New York's inland "coastline," from west to east] , Presque Isle [in far NW Pennsylvania] , Wind and waves have moved sand along the shore of Lake Erie over thousands of years and piled it up on a presumed underwater ridge to form this long, curved spit of dunes and bays., Niagara Falls , Runoff water from melting glaciers flowing over the Niagara Escarpment cut back into the capping limestone, forming the 7 mile long Niagara Gorge. The Niagara River plunges over 160' high Niagara Falls and still drains the Great Lakes Basin through the gorge., Blind Bays , High volumes of glacial meltwater carved deep gorges along the edge of the lake. Release of the weight of the ice as it melted allowed the compressed surface to rebound, tilting the land to the south and flooding these gorges to form large estuaries as seen in Irondequoit Bay., Drumlins/Bluffs , The last advancing ice sheet formed earlier glacial deposits into cigar shaped hills called drumlins. Where these drumlins meet the lakeshore they are being eroded by wind and waves into craggy fins and gullies., Dunes , Glacial meltwater was dammed by rock scarps and end moraines forming the large glacial Lake Iroquois. Torrential floods carried sediments downstream when the dam was breached. Prevailing westerly winds winnowed out the sands and piled them up in dunes., Thousand Islands , The Thousand Islands are bumps in the fractured and eroded strip of ancient bedrock called the Frontenac Arch. The arch connects Canadian Shield bedrock with the Adirondack Dome, an uplifted rock mass that eroded overlying sedimentary beds and exposed these billion year old rocks., ROCK TYPES , Glacial Deposits , Clays, silts, sands, pebbles, cobbles, boulders, and mixed soil materials (till) carried from northern locations, dropped from the melting ice, washed into deltas, kames and eskers by meltwater, deposited in mounds and ridges, and shaped into drumlins cover the entire Trail. The areas where the deposits are most scenic are highlighted by the stippled pattern., Sedimentary , Limestones, shales, siltstones, sandstones and conglomerates; sediments are "lithified" (cemented together) by compaction and mineral precipitates, and accumulate in layers, the lowest layers being the oldest and the upper layers the youngest., Igneous/Metamorphic , Non-layered rocks with crystalline texture. Igneous rocks originated deep in the Earth and are made of silica, quartz, feldspar and other crystallized minerals. Metamorphic rocks are changed or re-crystallized from existing rocks which have been subjected to heat, pressure and/or chemical activity., [Small notes along the Trail/coastline map are not transcribed]