The land below and around the ice

The geology of Greenland reflects a history that stretches back over nearly four billion years. By far the greatest part of the sub-continent is made up of crystalline rocks of the Precambrian shield. Fjords and valleys that cross the present day shield were formed by river erosion and later deepened by glacial erosion during the many advances and retreats of the Inland Ice. The glaciers also erode the landscape today, as can be seen at the ice margin around Ilulissat.