Title Bar: Illustrated Glossary of Alpine Glacial 
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An accumulation of till at the terminus or snout of a glacier.

End moraines in alpine areas tend to form ridges, but the actual size and appearance of the ridges may vary considerably depending on the amount of time during which the glacier margin was stationary, the amount of material the glacier was transporting, and the rate of ice flow. If the glacier margin is stationary (i.e. the size of the glacier does not change) for a long time period, a large moraine (ridge) may form. If the glacier margin was stationary for just a year or several months, a well-defined ridge may not form. Glaciers transporting large amounts of sediment are more likely to form large end moraines (ridges) compared to glaciers transporting only small amounts of sediment, all other factors being equal. Glaciers with fast flow rates are more likely to form large end moraines (ridges) than glaciers with slow flow rates, all other factors being equal.

End moraines in alpine areas generally stretch across the valley (from one side of the valley to the other side of the valley) and may curve slightly downhill in the center due to the faster ice flow in the center of the glacier compared to ice flow along the margins of the glacier. Two different types of end moraines are terminal moraines and recessional moraines. The terminal moraine marks the farthest extent of glacial advance and thus is located at the lowest elevation. Recessional moraines form when glaciers are temporarily stationary during periods of overall glacial retreat and thus are located at higher elevations than the terminal moraine. After glaciers retreat, these end moraines may be greatly modified or destroyed by subsequent fluvial erosion.

The photo shows a small end moraine associated with the glacier at the base of Clements Mountain. Topographic maps show glaciers using blue contour lines with a dashed blue line marking the borders of the glacier. Brown speckles symbolize all types of moraines, as is the case with the end moraine on this topographic map. In this photo you are looking toward the southwest, thus you see the northernmost part of the moraine shown on the map. Although end moraines may form along the entire width of the glacier terminus (snout), as a glacier retreats, meltwater flowing out from the glacier may erode away parts of the end moraine giving it a discontinuous appearance (as in this example). There is no camera on the map to show where the picture was taken from because this location is off the map.

Photo: K.A. Lemke. Used with permission.

Photo: end moraine Topographic Map: End Moraine

The moraine deposits in this second photo were left by Sperry Glacier when it was larger than at the time the photo was taken. These moraine deposits clearly show on the topographic map as lines of brown speckles. The end moraines provide you with an indication of the former size of the glacier. In places, rivers have eroded through the end moraine creating breaks in the ridge. Although many end moraines form as ridges stretching across alpine valleys, these ridges are slowly dissected and eroded by present-day streams. Eventually, streams may completely obliterate the moraines.

Photo: end moraine

Photo: K.A. Lemke. Used with permission.

Topographic map: end moraine
| More Examples of End Moraines |

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All commercial rights reserved. Copyright 2010 by Karen A. Lemke. Earlier copyright 2002 by Karen A. Lemke, and 1998 by Karen A. Lemke and Linda Freeman.
Last updated June 2010 KAL.