Trapped In Time - Chapter 127

Often, the tectonic action of crustal extension has created an alternating series of parallel grabens and horsts that form elongate basins alternating with mountain ranges. Not only does this promote the creation of lakes by the disruption of preexisting drainage networks, it also creates within arid regions endorheic basins that containing salt lakes (also called saline lakes). They form where there is no natural outlet, a high evaporation rate and the drainage surface of the water table has a higher-than-normal salt content. Examples of these salt lakes on your Earth is the Great Salt Lake and the Dead Sea. Another type of tectonic lake caused by faulting is sag ponds.

Volcanic lakes

Volcanic lakes are lakes that occupy craters and maars or larger basins, e.g. calderas, created by volcanic activity. Crater lakes are formed in volcanic craters and calderas, which fill up with precipitation more rapidly than they empty via either evaporation, groundwater discharge, or combination of both. Sometimes the latter are called caldera lakes, although often no distinction is made. An example of this on your Earth is the Crater Lake in Oregon, the caldera of Mount Mazama. The caldera was created in a massive volcanic eruption that led to the subsidence of Mount Mazama around 4860 BCE. Other volcanic lakes are created when either rivers or streams got dammed by lava flows or volcanic lahars. The Malheur Lake, Oregon was created when the flow of lava blocked the Malheur River.

Glacial lakes

Glacial lakes are lakes created by the direct action of glaciers and continental ice sheets. A wide variety of glacial processes create enclosed basins. As a result, there are a wide variety of different types of glacial lakes and it is often difficult to differentiate between different types of glacial lakes and lakes influenced by other activities. The general types of glacial lakes that have recognized are lakes in direct contact with ice; glacially carved rock basins and depressions; moraine and outwash lakes; and glacial drift basins. Glacial lakes are the most numerous lakes in your world. Glacial lakes include proglacial lakes, subglacial lakes, finger lakes, and epishelf lakes. Epishelf lakes are highly stratified lakes in which a layer of freshwater, derived from ice and snow melt and is dammed behind an ice shelf that is attached to the coastline. They are mostly found in your Antarctica.

Fluvial lakes

Fluvial (or riverine) lakes are lakes produced by running water. These lakes include plunge pool lakes, fluviatile dams and meander lakes.

Oxbow lakes

The most common type of fluvial lake is a crescent-shaped lake called an oxbow lake due to the distinctive curved shape. They can form in river valleys as a result of meandering of the river. The slow-moving river forms a sinuous shape as the outer side of bends are eroded away more rapidly than the inner side. Eventually a horseshoe bend is formed and the river cuts through the narrow neck. This new passage then forms the main passage for the river and the ends of the bend become silted up, thus forming a bow-shaped lake.

Fluviatile dams

These form where sediment from a tributary blocks the main river.

Lateral lakes

These form where sediment from the main river blocks a tributary, usually in the form of a levee.

Solution lakes

A solution lake is a lake occupying a basin formed by surface dissolution of bedrock. In areas underlain by soluble bedrock, its solution by precipitation and percolating water commonly produce cavities. These cavities frequently collapse to form sinkholes that form part of the local karst topography. Where groundwater lies near the grounds surface, a sinkhole will be filled with water as a solution lake. If such a lake consists of a large area of standing water that occupies an extensive closed depression in limestone, it is also called a karst lake. Smaller solution lakes that consist of a body of standing water in a closed depression within a karst region are known as karst ponds. Limestone caves often contain pools of standing water, which are known as underground lakes. Classic examples of solution lakes are abundant in the karst regions on your Earth are at the Dalmatian coast of Croatia and within large parts of your Florida.

Landslide lakes

Landslide lakes are lakes created by the blockage of a valley by either mudflows, rockslides. Such lakes are common in mountainous regions. Although landslide lakes may be large and quite deep, they are typically short-lived. An example of a landslide lake is your Quake Lake in southwestern Montana in the United States. This was formed as a result of the 1959 Hebgen Lake earthquake.

Aeolian lakes

Aeolian lakes are lakes produced by wind action. They are found mainly in arid environments although some aeolian lakes are relict landforms indicative of arid paleoclimates. Aeolian lakes consist of lake basins dammed by wind-blown sand; interdunal lakes that lies between well-oriented sand dunes; and deflation basins formed by wind action under previously arid paleoenvironments. Your Moses Lake, Washington, is an example of a lake basins dammed by wind-blown sand.

Shoreline lakes

Shoreline lakes are generally lakes created by blockage of estuaries or by the uneven accretion of beach ridges by longshore and other currents. They include maritime coastal lakes, ordinarily in drowned estuaries; lakes enclosed by two tombolos or spits connecting an island to the mainland; lakes cut off from larger lakes by a bar; or lakes divided by the meeting of two spits.

Organic lakes

Organic lakes are lakes created by the actions of plants and animals. On the whole they are relatively rare in occurrence and quite small in size. In addition, they typically ephemeral features relative to the other types of lakes. The basins in which organic lakes occur are associated with beaver dams, coral lakes, or dams formed by vegetation.

Peat lakes

Peat lakes are a form of organic lake. They form where a buildup of partly decomposed plant material in a wet environment leaves the vegetated surface below the water table for a sustained period of time. They are often low in nutrients and mildly acidic, with bottom waters low in dissolved oxygen.

Anthropogenic lakes

Anthropogenic lakes are artificially created lakes formed by human activity. They can be the result of intentional damming of rivers and streams or subsequent filling of abandoned excavations by either groundwater, precipitation, or a combination of both.