A glacial lake is a lake with origins in a melted glacier. Near the end of the last glacial period, roughly 10,000 years ago, glaciers began to retreat. A retreating glacier often left behind large deposits of ice in hollows between drumlins or hills. As the ice age ended, these melted to create lakes. This is apparent in the Lake District in Northwestern England where post-glacial sediments are normally between 4 and 6 metres deep. These lakes are often surrounded by drumlins, along with other evidence of the glacier such as moraines, eskers and erosional features such as striations and chatter marks.
The scouring action of the glaciers pulverizes minerals in the rock over which the glacier passes. These pulverized minerals become sediment at the bottom of the lake, and some of the rock flour becomes suspended in the water column. These suspended minerals support a large population of algae, making the water appear green.
These lakes are clearly visible in aerial photos of landforms in:
- New Zealand
- United Kingdom
and other regions that were glaciated during the last ice age. The coastlines near these areas are typically very irregular, reflecting the same geological process.
By contrast, other areas have fewer lakes that often appear attached to rivers. Their coastlines are smoother. These areas were carved more by water erosion.
As seen in the English Lake District, the layers of the sediments at the bottom of the lakes can then tell you the rate of erosion by taking into account the rate of erosion of the glacier and its subsequent placement of the sediment. The elemental make up of the sediments are not associated with the lakes the themselves, but by the migration of the elements within the soil, such as iron and manganese.
Sediment deposition can also be influenced by animal activity; including the distribution of biochemical elements, which are elements that are found in organic organisms, such as phosphorus and sulfur.
The less halogen and boron found in the sediments accompanies a change in erosional activity. The rate of deposition reflects the amount of halogen and boron in the deposited sediments.
Other articles related to "glacial lake, glacial, lake, lakes, glacial lakes":
... had they gone a bit further they would have discovered the true cause of the river valley to be a glacial lake at the foot of the mountain ... The river valley cut through 300 feet (91 m) of basalt was cut by a catastrophic glacial lake overflow and not by slow and gradual processes ... but today recognized to have been made quickly by catastrophic glacial flooding ...
... The Glacial Lake Souris occupied the basin of the Souris River from the most southern portion of this river's loop in North Dakota to its elbow in Manitoba ... The length of Lake Souris was about 170 miles, from latitude 48° to latitude 50°35', and its maximum width, north of Turtle Mountain, was nearly 70 miles ... It was situated near the far southeast corner of the large glacial Lake Agassiz, separated from it by another small glacial body, Glacial Lake Hind ...
... landscape of central New York is primarily a result of glacial activity between one million and ten thousand years ago ... The moraine formed a series of lakes in the valleys ... At an elevation of about 900 feet, the glacial lakes filling the finger lakes valleys joined to form an interlocking system of lakes to the west (glacial Lake Warren ) ...
... Glacial Lake Aitkin was also a product of the recession of the St ... significant portions of its history was contiguous with Glacial Lake Upham ... The lake bed is now a sandy and clayey plain ...
Famous quotes containing the word lake:
“Such were the first rude beginnings of a town. They spoke of the practicability of a winter road to the Moosehead Carry, which would not cost much, and would connect them with steam and staging and all the busy world. I almost doubted if the lake would be there,the self-same lake,preserve its form and identity, when the shores should be cleared and settled; as if these lakes and streams which explorers report never awaited the advent of the citizen.”
—Henry David Thoreau (18171862)