Medial moraine
Topic: Landforms and their Evolution: Rivers, Groundwater, Glaciers, Waves and Wind · NCERT: Class 11, Ch 6 "Landforms and their Evolution"
Meaning
A medial moraine is a ridge of glacial till that runs down the centre of a glacial valley, with a lateral moraine on each side. It usually forms where two glaciers meet and flow on as one. The inner lateral moraines of the two glaciers join and travel down the middle of the combined ice as a dark stripe of debris. When the ice melts, this stripe is dropped on the valley floor. It is less perfectly formed than a lateral moraine. Sometimes it is hard to tell apart from ground moraine, which is an uneven sheet of till over the valley floor.
Example
The Siachen glacier in the Karakoram is about 76 km long. Where its tributary glaciers join it, dark bands of medial moraine run along its surface.
Don't confuse with
- Lateral moraine: a lateral moraine lies along the sides of the valley. A medial moraine runs down the middle and forms only where glaciers merge.