Isostasy

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This is a short topic about a process known as Isostasy. As with most things in the environment this is actually a cycle. So what is Isostasy? Well Isostasy is the idea that when a heavy mass is on the crust it will become depressed. The most often used example is that of ice-sheets.

Firstly an ice-sheet forms on top of the crust, which is floating on the liquid like mantle (mantle)(see tectonics):



The weight of the ice-sheet causes the crust to become depressed:



Eventually the ice begins to melt and a lake forms in inside the depression:



The liquid in the lake is far lighter than that of the ice and so the pressure from the mantle pushes the crust upwards. This results in the water running out of the lake and down to the sea:



Eventually the crust (crust) will return to its original flat form and it is likely that a new ice-sheet will form and the process will happen again.

This cycle happens over a very long time and is a good example of Isostasy (Isostasy). Please note that this process can occur when any large mass is formed on the crust, but ice is the most common reason for its occurrence.