Drumlin

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Drumlin

A drumlin (Irish droimnín, a little hill ridge) is an elongated whale-shaped hill

Hill

A hill is a landform that extends above the surrounding terrain, in a limited area. Hills often have a distinct Summit , although in areas with Escarpment a hill may refer to a particular section of scarp slope without a well-defined summit ....
formed by glacial

Glacier

A glacier is a large, slow-moving mass of ice, formed from compacted layers of snow, that slowly deforms and flows in response to gravity and high pressure....
action.

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A drumlin (Irish droimnín, a little hill ridge) is an elongated whale-shaped hill

Hill

Glacier

A glacier is a large, slow-moving mass of ice, formed from compacted layers of snow, that slowly deforms and flows in response to gravity and high pressure....
action. Its long axis is parallel with the movement of the ice, with the blunter end facing into the glacial movement. Drumlins may be more than 45 m (150 ft) high and more than 0.8 km (½ mile) long, and are often in drumlin field

Drumlin field

A drumlin field is a cluster of dozens to hundreds of similarly shaped, sized and oriented drumlins, also called a drumlin swarm. Drumlins are one type of landform that indicate Ice age glaciation....
s of similarly shaped, sized and oriented hills. Drumlins usually have layers indicating that the material was repeatedly added to a core, which may be of rock

Rock (geology)

In geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock....
or glacial till.

There are many theories

Theory

For a more detailed account of theories as expressed in formal language as they are studied in mathematical logic see Theory A theory, in the general sense of the word, is an analytic structure designed to explain a set of observations....
as to the exact mode of origin and plenty of controversy among geologists interested in geomorphology

Geomorphology

Geomorphology is the scientific study of landforms and the processes that shape them. Geomorphologists seek to understand why landscapes look the way they do: to understand landform history and dynamics, and predict future changes through a combination of field observation, physical experiment, and numerical mathematical model....
. Some consider them a direct formation of the ice, while a theory proposed since the 1980s by John Shaw and others postulates creation by a catastrophic flooding release of highly pressurized water flowing underneath the glacial ice. Either way, they are thought to be a waveform

Waveform

Waveform means the shape and form of a signal such as a wave moving in a solid, liquid or gaseous medium.In many cases the medium in which the wave is being propagated does not permit a direct visual image of the form....
(similar to ripples of sand at the bottom of a stream). It is also poorly understood why drumlins form in some glaciated areas and not in others. They are often associated with ribbed moraines

Ribbed moraines

A Rogen moraine is a subglacially formed type of landform, that mainly occur in Fennoscandia, Scotland, Ireland and Canada. They cover large areas that have been covered by ice, and occur mostly in what is believed to be the central areas of the ice sheets....
.

Drumlins are common in New York

New York

The State of New York is a U.S. state in the Mid-Atlantic States and Northeastern United States regions of the United States and is the nation's List of U.S....
, the lower Connecticut River valley

Connecticut River

The Connecticut River is the largest river in New England, flowing south from the Connecticut Lakes in northern New Hampshire, along the border between New Hampshire and Vermont, through Western Massachusetts and central Connecticut into Long Island Sound at Old Saybrook, Connecticut....
, eastern Massachusetts

Massachusetts

The Commonwealth of Massachusetts is a U.S. state located in the New England region of the Northeastern United States United States. It borders Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north....
, the Monadnock Region

Monadnock Region

The Monadnock Region is a region in southwestern New Hampshire. It is named after Mount Monadnock, the major geographic landmark in the region. The Monadnock Region is composed of all of Cheshire County, New Hampshire and western Hillsborough County, New Hampshire....
of New Hampshire

New Hampshire

New Hampshire is a U.S. state in the New England region of the Northeastern United States United States of America. The state was named after the southern English Counties of England of Hampshire....
, Minnesota

Minnesota

Minnesota is a U.S. state in the Midwestern United States of the United States. The twelfth largest state by area in the U.S., it is the twenty-first most populous, with just over five million residents....
, Wisconsin

Wisconsin

Wisconsin is one of the fifty U.S. state in the United States of America, located in the north central part of the United States. It borders two of the five Great Lakes and four U.S....
, Alberta

Alberta

Alberta is one of Canada Canadian Prairies Provinces and territories of Canada. It became a province on September 1, 1905.Alberta is located in western Canada, bounded by the provinces of British Columbia to the west and Saskatchewan to the east, the Northwest Territories to the north, and the U.S....
, Southern Ontario

Southern Ontario

Southern Ontario is the portion of the Canada province of Ontario lying south of the French River and Algonquin Park. It is the southernmost region of Canada....
, Nova Scotia

Nova Scotia

Nova Scotia is a Canadian Provinces and territories of Canada located on Canada's southeastern coast. It is the most populous province in Atlantic Canada....
, Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe. Poland is bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian Enclave and exclave, to the north....
, Estonia

Estonia

Estonia , officially the Republic of Estonia is a country in the Baltic region of Northern Europe. It is bordered to the north by Finland across the Gulf of Finland, to the west by Sweden across the Baltic Sea, to the south by Latvia , and to the east by the Russia ....
, around Lake Constance

Lake Constance

Under the designation Lake Constance one summarizes the three independent Body of water Obersee , Untersee and Seerhein , lying in the northern Alps foreland....
north of the Alps

Alps

The Alps is the name for one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east; through Italy, Switzerland, Liechtenstein and Germany; to France in the west....
, Ireland

Ireland

Hindsholm

Hindsholm is a peninsula forming the north-eastern extremity of the Denmark island of Funen. It is bound to the south by the Kerteminde Fjord but linked to the rest of the island in the south-west. It belongs to Kerteminde municipality....
in Denmark, Finland

Finland

Finland , officially the Republic of Finland , is a Nordic countries situated in the Fennoscandian region of northern Europe. It borders Sweden on the west, Russia on the east, and Norway on the north, while Estonia lies to its south across the Gulf of Finland....
and Patagonia

Patagonia

Patagonia is a geographic region containing the southernmost portion of South America. Located in Argentina and Chile, it comprises the Andes mountains to the west and south, and plateaux and low plains to the east....
. Those in North America are regarded as a creation of the last Wisconsin

Wisconsin glaciation

The last glacial period was the most recent glacial period within the Quaternary glaciation, occurring in the Pleistocene epoch. It began about 110,000 years ago and ended between 10,000 and 15,000 Before Present....
ice age

Ice age

The general term "ice age" or, more precisely, "glacial age" denotes a geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in an expansion of continental ice sheets, polar ice sheets and alpine glaciers....
.

The islands of Boston Harbor Islands National Recreation Area are drumlins that became islands when sea levels rose as the glaciers melted. Clew Bay

Clew Bay

Clew Bay is a natural ocean bay in County Mayo, Ireland. It contains Ireland's best example of sunken drumlins. According to tradition, there is an island in the bay for every day of the year....
in Ireland

Ireland

Ireland is the List of islands by area in Europe, and the twentieth-largest island in the world. It lies to the north-west of continental Europe and is surrounded by hundreds of islands and islet....
is a good example of a 'drowned drumlin' landscape where the drumlins appear as islands in the sea, forming a 'basket of eggs' topography. Drumlins are typically aligned parallel to one another, usually clustered together in numbers reaching the hundreds or even thousands.

Drumlin formation has recently been observed for the first time in Antarctica

Antarctica

Antarctica is Earth's southernmost continent, overlying the South Pole. It is situated in the Antarctica of the southern hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean....
in the Rutford Ice Stream. A similar formation, with a more resilient (generally composed of igneous or metamorphic

Metamorphic

The term Metamorphic can be associated with a number of meanings:*Metamorphic rock: The term for rocks that have been transformed by extreme heat and pressure....
rock) core, is a crag

Crag and tail

A crag is a rocky hill or mountain, generally isolated from other high ground. Crags are formed when a glacier or ice-sheet passes over an area that contains a particularly resilient chunk of rock ....
.

Drumlin soil classification consists of a thin A soil horizon

Soil horizon

A soil horizon is a specific layer in the soil which measures parallel to the soil surface and possesses physical characteristics which differ from the layers above and beneath....
and a thin Bw horizon. The C horizon is close to the surface, allowing parent material

Parent material

Parent material, in soil science, means the underlying geological material in which soil horizons form. Soils typically get a great deal of structure and minerals from their parent material....
to emerge to the surface through weathering

Weathering

Weathering is the decomposition of earth Rock , soils and their minerals through direct contact with the planet's atmosphere. Weathering occurs in situ, or "with no movement", and thus should not be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice, wind, and gravity....

Footnotes

External links

, image from Geological Survey of Canada
Geological Survey of Canada

The Geological Survey of Canada is part of the Earth Sciences Sector of Natural Resources Canada. GSC is responsible for performing Geology surveys of the country, developing Canada's natural resources and protecting the environment....
Canadian Landscapes Photo Collection

Drumlin

See also

Footnotes

External links