What Is a Depositional Landform?
What is moved easily by rivers and streams?
Hi I’m Geologist John Swanson for About.com and today I am going to talk about depositional landforms. Landforms are formed in many ways. One of the numerous ways land is formed is by what is called deposition.A depositional landform is one that is composed of material that has been washed ashore. It’s name gives a great hint at its specific formation. Deposition comes from the word deposit. So the materials making up the landform were deposited there through one form or another.Sediment or metamorphic rocks and stones often compose a depositional landform. There are many famous places on our globe that can be identified as depositional landforms. You can think of depositional landforms as ones that were slowly built by geologic and natural forces over a long period of time. Bit by bit, they slowly build up.You can contrast depositional landforms with other landforms that are formed by either erosion or tectonic forces. But where does all this sediment come from that is then deposited elsewhere forming depositional landforms? One major and common source is from the movement of ancient glaciers. As the glaciers thaw and refreeze, their shape changes and they grind against the rock. Due to friction, rock will chip and break into smaller pieces, forming sediment of varying sizes.Of course another common force that causes sediment is the ocean. Though certainly not as visible or dynamic as glacial erosion, the oceanic movements against shorelines causes rocks to be slowly broken and dismantled as well. Water is the main force that causes the deposition of sediments thereby causing landforms.Rivers and streams easily move sediment. As the rivers and streams slow, the once suspended sediments fall to the bed and begin to pile up over time. Over long periods, this slow build up can drastically transform the landscape. Hopefully now you have a better understanding of depositional landforms.Thanks for watching. If you’d like to learn more, please find us on the web at about.com.