Download Long Island - Introduction to Oceanography - Lecture Slides and more Slides Oceanography in PDF only on Docsity! Long Island: Home Sweet Home • You know that Long Island is an island, but do you know about the origin of Long Island and the coastal features that surround it? Great South Bay Peconic Bay Long Island Sound Shinnecock Bay www.loving-long-island.com Docsity.com In the beginning… • The Atlantic Ocean basin originated ~200-135 million years ago (mya) as the supercontinent Pangaea began drifting apart from seafloor spreading http://upload.wikimedia.org/wikipedia/commons/8/8e/ Pangea_animation_03.gif Docsity.com Docsity.com The geological history of Long Island • 200 million years of weathering drastically reduced these mountains in size and deposited large amounts of sediment along the edge of the expanding Atlantic Ocean • Gradually, Long Island originated as a river valley as sediments were supplied by the erosion of these coastal plains and the Appalachian Mountains – served as a foundation for present-day Long Island Docsity.com The Last ‘Ice Age’ • ~110,000 - ~10,000 years ago marked the last (most recent) glacial period • During this time, much of the Northern Hemisphere (and to a lesser extent, the Southern Hemisphere) was covered in glaciers • Under the extremely cold conditions, these glaciers grew, or advanced Docsity.com Stuck between a rock and a hard place • The melting of the Wisconsin ice sheet ~20,000 years ago deposited rocks and sediment from within the rocks forming glacial moraines • Forms LI’s north shore and ‘backbone’ *Moraines * * Docsity.com • The water melting from the giant ice sheet formed Lake Connecticut (where LIS now stands) • As more and more of the ice sheet melted, sea level rose and eventually covered over the coastal plain creating Long Island Sound (saline) ~12,000 years ago Docsity.com The origin of glacial deposits
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Shinnecock Bay; June 1938 Docsity.com Shinnecock Bay; September 1938 after the Great Hurricane Storm surge carved out a large section of the barrier island separating Shinnecock Bay from the Atlantic Ocean Shinnecock Inlet Docsity.com The geological future of Long Island • As sea levels rise, more and more of Long Island will become submerged (why you need flood insurance if own a house on the south shore…) • Alternatively, if sea levels decline, more and more of Long Island would be exposed • Earthquakes from isostatic rebound and ancient faults continue to occur Docsity.com
