Kame and Kettle Topography
What is Kame and Kettle topography?
Kames and kettles are landforms created by continental glaciers. Glaciers carry a large amount of till. Glacial till is unsorted sediments of varying size that become part of a glacier as it erodes and plucks rocks in the landscape. The result is that glaciers are less like a block of ice, and more like a moving surface of ice, sediments, and subglacial streams. Glaciers deposit sediment and leave isolated ice blocks as they recede, leading to the formation of kames and kettles. Kame and kettle topography is often located on end moraines (locations where sediment accumulates at the end of a glacier) because sediment is deposited when glaciers recede. Kames are mounds where till is deposited and kettles are depressions formed by ice being trapped under till Easterbrook (1999). Together, they form a bump and depression landscape often containing many lakes.
This aerial photo shows the basic shape of kames and kettles. Kames are defined by their conic shape. Both kames and kettles have a large variety of shapes and sizes.
Kames and kettle topography is interchangeably called knob-and-kettle topography due to the conic shape of kames. The grey till is visible in the side view of the cross section. Notice that kettles can also form on elevated surfaces such as end moraines (Easterbook, 1999).
Kame Formation
Kames form when till accumulates on top of ice and fills in a depression left by the melted ice. This results in an elevated mound, often of different material than the surrounding soil (Easterbrook, 1999). In the diagram to the right, the first image shows the formation of the depression. The second image shows the mound after filling the depression. The third image shows the formation of a bog next to the kame hill. Bogs can often form in kettle holes if a depression is shallow but still intersects the water table.
This is an example of a kame in Yellowstone, WY. Note the somewhat conic shape of the mounds and elevation compared to the surrounding land. Many kames can become obscured by high vegetation which depends largely on the soil and climate.
Kettle Formation
Kettles are formed when ice becomes trapped under till and erodes downward (Fig. 5). Glaciers commonly drop chunks of ice known as dead ice while receding due to variable rates of glacial melt and presence of subglacial features. Dry kettles are known as kettle holes. Kettles that intercept the water table fill with water and are known as kettle lakes (Almon and Friend, 2015.
Kettles are very common in certain regions of the world. Minnesota, the acclaimed land of 10,000 lakes is filled with kettles, most of which are kettle lakes (Hoff, n.d.). When the water table is high, kettle lakes, often formed in closely spaced areas (Fig. 6). Although kettle lakes are often small, they can get over 100 feet deep (Ice Age Trail, n.d.)! Clearly the erosional power of ice is not to be underestimated.
Examples of Kames and Kettles
The kames present at Holy Hill are abnormally large. The image on the left is a topographic map of Holy Hill. Although kames are sometimes found near kettles to form kame and kettle topography, they also exist independently and are often well-spaced.
Fig. 8: Holy Hill Kame created by Troutman, (2021) using API and Sketchfab.
This is an interactive 3D model of the kames at Holy Hill. Note the difference between the surrounding topography and these raised mounds.
Fig. 9 Kettle and Kame topography near Independence, Minnesota. Photos are by Troutman, (2021) using Google Earth Pro. The left image was created using the USGS topographic map.
This sliding map illustrates how useful topographic map can be in examining kame and kettle topography. The topographic map illustrates extensive kames and kettles while the satellite image makes it hard to determine the presence of kames to the untrained eye. Also notice that many of the kettles visible on the topographic map are kettle holes, not kettle lakes. This is because they do not intersect the water table and thus remain dry. Kettles can be identified in glaciated areas on a topographic map by examining hatchered marks. These marks indicate lower elevations and represent a depression on the map.
Explore Kame and Kettle Topography
Fig. 10: Image of kame and kettle topography taken by Troutman, (2021) using Google Earth Pro.
Fig. 11: Kame and Kettle Topography near Kenosee Lake, Saskatchewan. Created by Troutman, (2021) using API and Sketchfab.