Geography of Long Island
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Long Island Long Island is a densely populated island in the southeastern region of the U.S. state of New York (state), New York, part of the New York metropolitan area. With over 8 million people, Long Island is the most populous island in the United Sta ...
is in southeastern
New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...
,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
, separated from the rest of the state by the
East River The East River is a saltwater tidal estuary in New York City. The waterway, which is actually not a river despite its name, connects Upper New York Bay on its south end to Long Island Sound on its north end. It separates the borough of Queens ...
and from
Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south. Its cap ...
by
Long Island Sound 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 from the Eas ...
. Long Island contains four counties, of which the western two are
boroughs A borough is an administrative division in various English-speaking countries. In principle, the term ''borough'' designates a self-governing walled town, although in practice, official use of the term varies widely. History In the Middle Ag ...
(
Queens Queens is a borough of New York City, coextensive with Queens County, in the U.S. state of New York. Located on Long Island, it is the largest New York City borough by area. It is bordered by the borough of Brooklyn at the western tip of Long ...
and
Brooklyn Brooklyn () is a borough of New York City, coextensive with Kings County, in the U.S. state of New York. Kings County is the most populous county in the State of New York, and the second-most densely populated county in the United States, be ...
) of New York City, and the other two (
Nassau Nassau may refer to: Places Bahamas *Nassau, Bahamas, capital city of the Bahamas, on the island of New Providence Canada *Nassau District, renamed Home District, regional division in Upper Canada from 1788 to 1792 *Nassau Street (Winnipeg), ...
and
Suffolk Suffolk () is a ceremonial county of England in East Anglia. It borders Norfolk to the north, Cambridgeshire to the west and Essex to the south; the North Sea lies to the east. The county town is Ipswich; other important towns include Lowes ...
) are mainly
suburb A suburb (more broadly suburban area) is an area within a metropolitan area, which may include commercial and mixed-use, that is primarily a residential area. A suburb can exist either as part of a larger city/urban area or as a separate ...
an.


Geology

Long Island, as part of the
Outer Lands The Outer Lands is the prominent terminal moraine archipelagic region off the southern coast of New England in the United States. This eight-county region of Massachusetts, Rhode Island, and New York, comprises the peninsula of Cape Cod and th ...
region, is formed largely of four spines of
glacial moraine A moraine is any accumulation of unconsolidated debris (regolith and rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice shee ...
, with a large, sandy outwash plain towards its barrier islands and the
Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
. These moraines consist of gravel and loose rock left behind during the two most recent pulses of
Wisconsin glaciation 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 Cor ...
some 21,000 years ago (19,000 BC). The northern moraine, which directly abuts the
North Shore of Long Island 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 centur ...
at points, is known as the
Harbor Hill moraine The Harbor Hill Moraine, in the geography of Long Island, forms the northern of two ridges along the "backbone" of Long Island. Description The Harbor Hill Moraine, skirting the North Shore, represents the terminal moraine of the most recen ...
. The more southerly moraine, known as the
Ronkonkoma moraine The Ronkonkoma Moraine, in the geography of Long Island, forms the southern of two ridges along Long Island's "backbone." Description The Ronkonkoma Moraine, a terminal moraine, predates the Harbor Hill Moraine (which reached Long Island during ...
, forms the "backbone" of Long Island; it runs primarily through the very center of Long Island, roughly coinciding with the length of the
Long Island Expressway Long may refer to: Measurement * Long, characteristic of something of great duration * Long, characteristic of something of great length * Longitude (abbreviation: long.), a geographic coordinate * Longa (music), note value in early music mensur ...
. The land to the south of this moraine to the South Shore is the
outwash plain An outwash plain, also called a sandur (plural: ''sandurs''), sandr or sandar, is a plain formed of glaciofluvial deposits due to meltwater outwash at the terminus of a glacier. As it flows, the glacier grinds the underlying rock surface and ca ...
of the last glacier. Part of this, known as the
Hempstead Plains The Hempstead Plains is a region of central Long Island, in what is now Nassau County, in New York State. It was once an open expanse of native grassland estimated to once extend to about . It was separated from the North Shore of Long Island by ...
, supported one of the few natural prairies to exist east of the
Appalachian Mountains The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They ...
. The
glaciers A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...
melted and receded to the north, resulting in the difference between the North Shore beaches and the South Shore beaches. The North Shore beaches are rocky from the remaining glacial debris, while the South Shore's are crisp, clear, outwash sand. Running along the center of the island like a spine is the moraine left by the glaciers. The glaciers also formed
Lake Ronkonkoma Lake Ronkonkoma is a hamlet and census-designated place (CDP) in Suffolk County, on Long Island, in New York, United States. The population was 20,155 at the 2010 census. Lake Ronkonkoma is mainly located in the Town of Brookhaven, but has ...
, a
kettle lake A kettle (also known as a kettle lake, kettle hole, or pothole) is a depression/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 gla ...
. The island's tallest natural point is
Jayne's Hill Jayne's Hill (also known as High Hill, West Hills, Oakley's Hill, and Janes Hill) is the highest point on Long Island, New York, with an elevation of between and above sea level. It is situated on the Harbor Hill moraine, a terminal moraine tha ...
near Melville, with an elevation of 400.9 feet (122.2 m) above
sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...
. Long Island is separated from the mainland by the
East River The East River is a saltwater tidal estuary in New York City. The waterway, which is actually not a river despite its name, connects Upper New York Bay on its south end to Long Island Sound on its north end. It separates the borough of Queens ...
, not in fact a river, but a
tidal strait A tidal strait is technically not a river but a strait connecting two oceans or seas. Tidal straits are narrow seaways through which tidal currents flow. Tidal currents are usually unidirectional but sometimes are bidirectional. They are frequent ...
. Long Island Sound forms the northern boundary of the island. Long Island contains a series of sand and gravel
aquifers An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...
, geologic formations which can hold, transmit, and yield water in usable quantities. All of Long Island's water supply comes from underground water reserves held in aquifers. Stacked one on top of the other like layers in a cake, three major and one minor aquifer make up the Long Island aquifer system. In sequence from shallowest to the deepest, the Long Island aquifers are: the Upper Glacial, the Magothy and the Lloyd Aquifers. All Long Island aquifers receive their fresh water from precipitation which takes from 25 to 1,000 years to migrate through the layers to the aquifers, which hold roughly 70 trillion US
gallons The gallon is a unit of volume in imperial units and United States customary units. Three different versions are in current use: *the imperial gallon (imp gal), defined as , which is or was used in the United Kingdom, Ireland, Canada, Austral ...
(260 km3)—enough to flood the entire surface of Long Island with more than 300 feet (90 m) of water—and can withstand long droughts that could dry up surface-water
reservoirs A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including control ...
like the ones that supply New York City. Almost four million gallons each day are taken from beneath Nassau and Suffolk Counties, providing the primary source of water for the resident population. While most homes are on a municipal water system, there are still many areas where homes have their own wells to provide water. Both Nassau and Suffolk counties have long recognized their dependence on the aquifers and have stipulated that recharge basins (known locally as
sump A sump is a low space that collects often undesirable liquids such as water or chemicals. A sump can also be an infiltration basin used to manage surface runoff water and recharge underground aquifers. Sump can also refer to an area in a cave ...
s) be built to collect ground water. Recharge basins are required and sized based upon the scale of any new development on Long Island. Due to
contamination Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc. Types of contamination W ...
associated with development, concern to preserve the quality of Long Island's
groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
has become the single most important factor limiting the region's growth. In '' United States v. Maine'' (1985), the
U.S. Supreme Court The Supreme Court of the United States (SCOTUS) is the highest court in the federal judiciary of the United States. It has ultimate appellate jurisdiction over all U.S. federal court cases, and over state court cases that involve a point o ...
treated the island as a
peninsula A peninsula (; ) is a landform that extends from a mainland and is surrounded by water on most, but not all of its borders. A peninsula is also sometimes defined as a piece of land bordered by water on three of its sides. Peninsulas exist on all ...
for the purposes of a boundary decision. Despite the legal decision, the
United States Board on Geographic Names The United States Board on Geographic Names (BGN) is a federal body operating under the United States Secretary of the Interior. The purpose of the board is to establish and maintain uniform usage of geographic names throughout the federal governm ...
considers Long Island an island, because it is surrounded by water.


Climate

Long Island has a climate similar to other coastal areas in the
Northeast The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A compass rose is primarily composed of four cardinal directions—north, east, south, and west—each se ...
; it has hot and humid summers and cool to cold winters. The Atlantic Ocean helps bring afternoon sea breezes to the immediate south shore that temper the heat in the warmer months. Severe thunderstorms are common, nevertheless, especially when they approach the island from the mainland areas of the
Bronx The Bronx () is a borough of New York City, coextensive with Bronx County, in the state of New York. It is south of Westchester County; north and east of the New York City borough of Manhattan, across the Harlem River; and north of the New Y ...
,
Westchester County Westchester County is located in the U.S. state of New York. It is the seventh most populous county in the State of New York and the most populous north of New York City. According to the 2020 United States Census, the county had a population o ...
and
Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south. Its cap ...
in the northwest. The
humid subtropical climate A humid subtropical climate is a zone of climate characterized by hot and humid summers, and cool to mild winters. These climates normally lie on the southeast side of all continents (except Antarctica), generally between latitudes 25° and 40° ...
zone (''Cfa'') according to the
Köppen climate classification The Köppen climate classification is one of the most widely used climate classification systems. It was first published by German-Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, notabl ...
has expanded to include the majority of the area of Long Island (including Brooklyn, Queens, most of Nassau, and parts of Suffolk) due to
global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, This area according to the
Trewartha climate classification The Trewartha climate classification (TCC) or the Köppen–Trewartha climate classification (KTC) is a climate classification system first published by American geographer Glenn Thomas Trewartha in 1966. It is a modified version of the Köppen ...
is oceanic (''Do''.) Trewartha requires at least eight months to be at least 50° F to be considered subtropical and Long Island has six to seven such months. The remainder of the island has January average below freezing and a hot-summer
humid continental climate A humid continental climate is a climatic region defined by Russo-German climatologist Wladimir Köppen in 1900, typified by four distinct seasons and large seasonal temperature differences, with warm to hot (and often humid) summers and freezing ...
(''Dfa''.) The
hardiness zone A hardiness zone is a geographic area defined as having a certain average annual minimum temperature, a factor relevant to the survival of many plants. In some systems other statistics are included in the calculations. The original and most wide ...
s are 7a and 7b.


Temperatures

Long Island temperatures vary from west to east, with the western part (Nassau County) of the island slightly warmer on occasions than the east (Suffolk County). This is due to two factors: the western part is closer to the mainland, and it is more densely developed, causing the "
urban heat island An urban heat island (UHI) is an urban or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. The temperature difference is usually larger at night than during the day, and is most apparen ...
" effect. The eastern part is cooler on most occasions due to moderation of the Atlantic Ocean and Long Island Sound, and its being less developed. On dry nights with no
clouds In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may com ...
or wind, the
Pine Barrens Pine barrens, pine plains, sand plains, or pineland areas occur throughout the U.S. from Florida to Maine (see Atlantic coastal pine barrens) as well as the Midwest, West, and Canada and parts of Eurasia. Perhaps the most well known pine-barre ...
in eastern Suffolk County can be almost 10 degrees Fahrenheit (6 degrees Celsius) cooler due to
Radiational cooling In the study of heat transfer, radiative cooling is the process by which a body loses heat by thermal radiation. As Planck's law describes, every physical body spontaneously and continuously emits electromagnetic radiation. Radiative cooling ha ...
.


Winter

Long Island sees the majority of its snowfall between the months of December and March, though it is not uncommon to see light snowfalls during mid-late November and early April. In many winters one or more intense storms (called a
Nor'easter A nor'easter (also northeaster; see below), or an East Coast low is a synoptic-scale extratropical cyclone in the western North Atlantic Ocean. The name derives from the direction of the winds that blow from the northeast. The original use o ...
) produce blizzard conditions with snowfalls of 1–2 feet (30–60 cm) and near-
hurricane A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
force winds. Average yearly snowfall totals range from approximately 25 to 40 inches (64–102 cm), with the north shore and western parts averaging more than the immediate south shore and the east end. In any given winter, however, some parts of the island could see up to 75 inches (190 cm) or more. There are also some very quiet winters, in which most parts of the island could see less than 15 inches (38 cm) when cold blasts happen.


Severe weather

Long Island is somewhat vulnerable to
hurricane A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
s. Its northern location and relatively cool waters tend to weaken storms to below hurricane strength by the time they reach Long Island, although despite this, some storms have made landfall at Category 1 or greater strength, including two unnamed Category 3 storms in 1938 (
New England Hurricane of 1938 The 1938 New England Hurricane (also referred to as the Great New England Hurricane and the Long Island Express Hurricane) was one of the deadliest and most destructive tropical cyclones to strike Long Island, New York, and New England. The storm ...
) and 1944,
Hurricane Donna Hurricane Donna, known in Puerto Rico as Hurricane San Lorenzo, was the strongest hurricane of the 1960 Atlantic hurricane season, and caused severe damage to the Lesser Antilles, the Greater Antilles, and the East Coast of the United States, ...
in 1960,
Hurricane Belle Hurricane Belle was a strong tropical cyclone that caused moderate damage across the East Coast of the United States in August 1976. In late July, a tropical wave emerged off the west coast of Africa. Traversing the Atlantic Ocean for mor ...
in 1976,
Hurricane Gloria Hurricane Gloria was a powerful hurricane that caused significant damage along the east coast of the United States and in Atlantic Canada during the 1985 Atlantic hurricane season. It was the first significant tropical cyclone to strike the n ...
in 1985,
Hurricane Bob Hurricane Bob was one of the costliest hurricanes in New England history. The second named storm and first hurricane of the 1991 Atlantic hurricane season, Bob developed from an area of low pressure near The Bahamas on August 16. The depressio ...
in 1991 (brushed the eastern tip) and
Hurricane Floyd Hurricane Floyd was a very powerful Cape Verde hurricane which struck the Bahamas and the East Coast of the United States. It was the sixth named storm, fourth hurricane, and third major hurricane in the 1999 Atlantic hurricane season. Floyd tr ...
in 1999. (There is debate among
climatologists Climatology (from Greek , ''klima'', "place, zone"; and , ''-logia'') or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. This modern field of study ...
as to whether
Hurricane Floyd Hurricane Floyd was a very powerful Cape Verde hurricane which struck the Bahamas and the East Coast of the United States. It was the sixth named storm, fourth hurricane, and third major hurricane in the 1999 Atlantic hurricane season. Floyd tr ...
made landfall as a Category 1 or as a very strong "almost hurricane strength"
tropical storm A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
. The official records note it as the latter.) Many other storms crossed the island directly at
tropical storm A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
strength, including
Hurricane Bertha The name Bertha has been used for ten tropical cyclones in the Atlantic Ocean. * Tropical Storm Bertha (1957), a moderate tropical storm that threatened areas devastated by Hurricane Audrey two months earlier, but did not become a hurricane and ca ...
in 1996 and
Hurricane Charley Hurricane Charley was the first of four separate hurricanes to impact or strike Florida during 2004, along with Hurricane Frances, Frances, Hurricane Ivan, Ivan and Hurricane Jeanne, Jeanne, as well as one of the strongest hurricanes ever to ...
in 2004. In September 2006, the remnants of Hurricane Ernesto swept through the area, causing several temporary power outages on parts of the island. In October 2012,
Hurricane Sandy Hurricane Sandy (unofficially referred to as ''Superstorm Sandy'') was an extremely destructive and strong Atlantic hurricane, as well as the largest Atlantic hurricane on record as measured by diameter, with tropical-storm-force winds spann ...
crossed the island making landfall over New Jersey as a post-tropical cyclone with hurricane-force winds. On Long Island, damage from the storm included severe flooding along the south shore and downed trees and utility poles on the north shore. Some thunderstorms can be extremely severe with tornadoes, although somewhat rare, but possible. In September 1998, a tornado hit Lynbrook; in August 1999, an F-2 tornado hit parts of Mattituck, in August 2005, a tornado hit Glen Cove; one year later in August 2006, a small tornado hit
Massapequa Massapequa (, ) is a hamlet and census-designated place (CDP) in the Town of Oyster Bay in Nassau County, on the South Shore of Long Island, in New York, United States. It is considered the anchor community of the Greater Massapequa area. The po ...
in Nassau County, and parts of
Amityville Amityville () is a village near the Town of Babylon in Suffolk County, on the South Shore of Long Island, in New York. The population was 9,523 at the 2010 census. History Huntington settlers first visited the Amityville area in 1653 due ...
, located in Suffolk County. On July 18, 2007, an F-1 tornado hit Islip Terrace and on September 27, 2006, a
waterspout A waterspout is an intense columnar vortex (usually appearing as a funnel cloud, funnel-shaped cloud) that occurs over a body of water. Some are connected to a cumulus congestus cloud, some to a cumuliform cloud and some to a cumulonimbus clou ...
was seen over Long Island Sound near
Port Jefferson Port Jefferson (informally known as "Port Jeff") is an incorporated village in the town of Brookhaven in Suffolk County, New York, on the North Shore of Long Island. Officially known as the Incorporated Village of Port Jefferson, the population ...
. In the wintertime, temperatures are sometimes warmer than areas further inland in Nassau County but Suffolk County will usually get at least one day where the temperature is below 0 °F (-18 °C) for low temperatures (especially in the night and early morning hours), In late July 2008 off the coast of Quogue on Dune Road, a water spout formed in the ocean; the related severe thunderstorms were the worst reported in years.


See also

*
Geography of New York The geography of New York (state) varies widely. Most of New York is dominated by farms, forests, rivers, mountains, and lakes. New York's Adirondack Park is larger than any U.S. National Park in the contiguous United States. Niagara Fall ...
*
Geography of New York City The geography of New York City is characterized by its coastal position at the meeting of the Hudson River and the Atlantic Ocean in a naturally sheltered harbor. The city's geography, with its scarce availability of land, is a contributing factor ...
*
Shelter Rock (North Hills, New York) Shelter Rock is a rock shelter of granite on the border of Manhasset and North Hills, New York, USA, 10 feet (3m) from Shelter Rock Road.Town of North Hempstead landmark sign, Shelter Rock Road. The rock is a glacial erratic estimated to weigh 1, ...


References

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