A kame delta (or ice-contact delta, morainic delta) is a
glacial
A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betwe ...
landform formed by a
stream of melt water flowing through or around a
glacier
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 ...
and
depositing material, known as
kame (stratified sequence of sediments) deposits. Upon entering a
proglacial lake
In geology, a proglacial lake is a lake formed either by the damming action of a moraine during the retreat of a melting glacier, a glacial ice dam, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around th ...
at the end (terminus) of a glacier, the river/stream deposit these sediments. This landform can be observed after the glacier has melted and the delta's asymmetrical triangular shape is visible. Once the glacier melts, the edges of the delta may subside as
ice
Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaqu ...
under it melts.
Glacial till
image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
is deposited on the lateral sides of the delta, as the glacier melts.
Associations
Kame deltas form in association with other glacial features such as
kettles and
esker
An esker, eskar, eschar, or os, sometimes called an ''asar'', ''osar'', or ''serpent kame'', is a long, winding ridge of stratified sand and gravel, examples of which occur in glaciated and formerly glaciated regions of Europe and North Ame ...
s.
Kettle lakes can form in between kame deltas. Eskers are remnants of old stream sediment flows that are exposed after the glacier has melted. These formations give indication that kame deltas formed during times of glaciation.
Formation
As a river or stream empties into a proglacial lake, sediments of silt, sand, and gravel are deposited into the lake. Since these sediments are stream deposited, the
stratigraphy of the
beds
A bed is an item of furniture that is used as a place to sleep, rest, and relax.
Most modern beds consist of a soft, cushioned mattress on a bed frame. The mattress rests either on a solid base, often wood slats, or a sprung base. Many be ...
will be well sorted. In these bed layers, sharp distinct size variations may occur in the clast size. This indicates a quick change in the river or stream's velocity.
Over time, depending on how deep the proglacial lake was and if the stream melt water was a constant, these sediments would build up and out of the lake. Sediments will then begin depositing against the terminus, or toe, of the glacier. This type of formation causes the asymmetrical triangular shaped mound, with a flat top. The longer side of the triangle, is the side that slopes down into the proglacial lake. The steeper side is the one that was up against the terminus. As the glacier retreats and the ice under the delta melts, the edges of the glacier will drop, causing a
fault line to be visible on the side of the kame delta.
Locations
The Fonthill Kame Delta is the highest point in the
Niagara Peninsula region.
Tree River, in Nunavut Canada.
Glacial Park,
Ringwood, IL.
Chenango River
The Chenango River is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 8, 2011 tributary of the Susquehanna River in central New York in the United States. It drains a dissec ...
, New York.
Springdale, Newfoundland and Labrador
Springdale is a town in Newfoundland and Labrador, Canada, which had a population of 2,965 people in 2021, up from 2,764 in the Canada 2006 Census. The community is located on the Northwestern shores of Hall's Bay in Central Newfoundland, near ...
See also
*
River delta
A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more ra ...
References
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External links
Glossary of important terms in glacial geology
Glaciology
Glacial landforms
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