Glacier, Svalbard - 19 - Medial Moraine

A medial (middle) moraine on a glacier. The dark line is a moraine which is made up of rocky debris that usually form at the edges of glaciers where erosion of the rock falls onto the glacier so making a side (lateral) moraine. The medial moraine arises where two glaciers merge and so two laterals join and become the middle or medial moraine of the new wider glacier. This dark line therefore signifies that two smaller glaciers have joined some distance upstream.