The Harbor Hill Moraine, in the geography of Long Island, forms the northern of two ridges along the "backbone" of Long Island. [1]
The Harbor Hill Moraine, in the geography of Long Island, forms the northern of two ridges along the "backbone" of Long Island. [1]
The Harbor Hill Moraine, skirting the North Shore, represents the terminal moraine of the most recent advance of the Wisconsinian glaciation, which reached its most southward advance about 18,000 years ago; the earlier Ronkonkoma Moraine, much cut through by outwash streams from the Harbor Hill Moraine, lies to the southeast. The Harbor Hill moraine is represented by the North Fork of eastern Long Island and in three disjunct sections farther east, Plum Island, Great Gull Island, and Fisher's Island. The western end is the Heights of Guwan in Brooklyn.
The Harbor Hill Moraine, named for its prominence at Harbor Hill, Roslyn, New York, the highest point in Nassau County, resulted from a lingering equilibrium stage in the glacier's episodic retreat, creating a stationary melting front; [2] the Long Island area became permanently free of glacial ice in the range of 13,000 to 12,000 years ago. [3]
The Harbor Hill Moraine intersects with the earlier Ronkonkoma Moraine at Lake Success: east of the lake the two moraines may be seen, but west of Lake Success the Harbor Hill moraine overrode and effaced the Ronkonkoma moraine. [4] South of the moraines is a broad outwash plain sloping towards the Atlantic Ocean, much of which has been submerged as ocean levels rose in the post-glacial period. The Harbor Hill Moraine forms the major drainage divide in Nassau County: streams to the northwest of the moraine flow into Long Island Sound, whereas those to the south empty into the series of bays or sounds behind the barrier islands and so into the Atlantic.
East Norwich is a hamlet and census-designated place (CDP) located within the Town of Oyster Bay in Nassau County, on the North Shore of Long Island, in New York, United States. The population was 2,792 at the time of the 2020 census.
Roslyn Estates is a village in the Town of North Hempstead in Nassau County, on the North Shore of Long Island, in New York, United States. It is considered part of the Greater Roslyn area, which is anchored by the Incorporated Village of Roslyn. The population was 1,318 at the 2020 census.
Roslyn Harbor is a village in Nassau County, on the North Shore of Long Island, in New York, United States. It is considered part of the Greater Roslyn area, which is anchored by the Incorporated Village of Roslyn. The population was 1,051 at the 2010 census.
Glaciology is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice.
Long Island Sound is a marine sound and tidal estuary of the Atlantic Ocean. It lies predominantly between the U.S. state of Connecticut to the north and Long Island in New York to the south. From west to east, the sound stretches 110 mi (180 km) from the East River in New York City, along the North Shore of Long Island, to Block Island Sound. A mix of freshwater from tributaries, and saltwater from the Atlantic Ocean, Long Island Sound is 21 mi (34 km) at its widest point and varies in depth from 65 to 230 feet.
Landforms are categorized by characteristic physical attributes such as their creating process, shape, elevation, slope, orientation, rock exposure, and soil type.
The Wisconsin Glacial Episode, also called the Wisconsin glaciation, was the most recent glacial period of the North American ice sheet complex. This advance included the Cordilleran Ice Sheet, which nucleated in the northern North American Cordillera; the Innuitian ice sheet, which extended across the Canadian Arctic Archipelago; the Greenland ice sheet; and the massive Laurentide Ice Sheet, which covered the high latitudes of central and eastern North America. This advance was synchronous with global glaciation during the last glacial period, including the North American alpine glacier advance, known as the Pinedale glaciation. The Wisconsin glaciation extended from approximately 75,000 to 11,000 years ago, between the Sangamonian Stage and the current interglacial, the Holocene. The maximum ice extent occurred approximately 25,000–21,000 years ago during the last glacial maximum, also known as the Late Wisconsin in North America.
A kettle is a depression or hole in an outwash plain formed by retreating glaciers or draining floodwaters. The kettles are formed as a result of blocks of dead ice left behind by retreating glaciers, which become surrounded by sediment deposited by meltwater streams as there is increased friction. The ice becomes buried in the sediment and when the ice melts, a depression is left called a kettle hole, creating a dimpled appearance on the outwash plain. Lakes often fill these kettles; these are called kettle hole lakes. Another source is the sudden drainage of an ice-dammed lake and when the block melts, the hole it leaves behind is a kettle. As the ice melts, ramparts can form around the edge of the kettle hole. The lakes that fill these holes are seldom more than 10 m (33 ft) deep and eventually fill with sediment. In acid conditions, a kettle bog may form but in alkaline conditions, it will be kettle peatland.
The North Shore of Long Island is the area along the northern coast of New York's Long Island bordering Long Island Sound. Known for its extreme wealth and lavish estates, the North Shore exploded into affluence at the turn of the 20th century, earning it the nickname the Gold Coast. Historically, this term refers to the affluent coastline neighborhoods of the towns of North Hempstead and Oyster Bay in Nassau County and Huntington in Suffolk County. Some definitions may also include the parts of Smithtown that face the Sound. The region is also largely coextensive with the Gold Coast region of Long Island, though this region excludes Smithtown, as the easternmost Gold Coast mansion is the Geissler Estate, located just west of Indian Hills Country Club in the Fort Salonga section of Huntington.
As part of New England, Connecticut has undergone much geologic change shaped by plate tectonics, volcanism, and glacial activity.
A terminal moraine, also called an end moraine, is a type of moraine that forms at the terminal (edge) of a glacier, marking its maximum advance. At this point, debris that has accumulated by plucking and abrasion, has been pushed by the front edge of the ice, is driven no further and instead is deposited in an unsorted pile of sediment. Because the glacier acts very much like a conveyor belt, the longer it stays in one place, the greater the amount of material that will be deposited. The moraine is left as the marking point of the terminal extent of the ice.
Glacial Lake Connecticut formed over what is now Long Island Sound and coastal Connecticut at the fore edge of the ice sheet of the Wisconsin glaciation, as the lobe of the Laurentide Ice Sheet began to retreat, some 18 to 20,000 years before present. It was dammed by the terminal moraine that now forms the spine of Long Island and Fishers Island. About 15,000 BP, the moraine dam that impounded Lake Connecticut failed; the outlet, known as The Race for its tidal rip currents, lies between the North Fork of Long Island and Fishers Island. For a time, much of the lake bed was exposed to wind-driven erosion: the cue is found in soundings that reveal regional unconformities in the sediment bed of Long Island Sound.
The glacial history of Minnesota is most defined since the onset of the last glacial period, which ended some 10,000 years ago. Within the last million years, most of the Midwestern United States and much of Canada were covered at one time or another with an ice sheet. This continental glacier had a profound effect on the surface features of the area over which it moved. Vast quantities of rock and soil were scraped from the glacial centers to its margins by slowly moving ice and redeposited as drift or till. Much of this drift was dumped into old preglacial river valleys, while some of it was heaped into belts of hills at the margin of the glacier. The chief result of glaciation has been the modification of the preglacial topography by the deposition of drift over the countryside. However, continental glaciers possess great power of erosion and may actually modify the preglacial land surface by scouring and abrading rather than by the deposition of the drift.
Fluvioglacial landforms are those that result from the associated erosion and deposition of sediments caused by glacial meltwater. These landforms may also be referred to as glaciofluvial in nature. Glaciers contain suspended sediment loads, much of which is initially picked up from the underlying landmass. Landforms are shaped by glacial erosion through processes such as glacial quarrying, abrasion, and meltwater. Glacial meltwater contributes to the erosion of bedrock through both mechanical and chemical processes.
Long Island is in southeastern New York, United States, separated from the rest of the state by the East River and from Connecticut by Long Island Sound. Long Island contains four counties, of which the western two are boroughs of New York City, and the other two are mainly suburban.
The geology of Massachusetts includes numerous units of volcanic, intrusive igneous, metamorphic and sedimentary rocks formed within the last 1.2 billion years. The oldest formations are gneiss rocks in the Berkshires, which were metamorphosed from older rocks during the Proterozoic Grenville orogeny as the proto-North American continent Laurentia collided against proto-South America. Throughout the Paleozoic, overlapping the rapid diversification of multi-cellular life, a series of six island arcs collided with the Laurentian continental margin. Also termed continental terranes, these sections of continental rock typically formed offshore or onshore of the proto-African continent Gondwana and in many cases had experienced volcanic events and faulting before joining the Laurentian continent. These sequential collisions metamorphosed new rocks from sediments, created uplands and faults and resulted in widespread volcanic activity. Simultaneously, the collisions raised the Appalachian Mountains to the height of the current day Himalayas.
The glacial series refers to a particular sequence of landforms in Central Europe that were formed during the Pleistocene glaciation beneath the ice sheets, along their margins and on their forelands during each glacial advance.
Lake Success is a kettle lake in Lake Success, in Nassau County, on Long Island, in New York, United States.
The Ronkonkoma Moraine, in the geography of Long Island, forms the southern of two ridges along Long Island's "backbone."
