Ice Age Ponds: History & Geology
25,000 years ago, western Herefordshire was invaded by a thick lobe of ice flowing down from the Welsh mountains. Higher ground to the north and south of the glacier was covered by a thinner ice sheet. Water melting and flowing away from the edge of the ice formed “meltwater” streams and the debris once carried by the ice was dropped in deposits called moraine.
Moraine is formed from the material torn from the rocks the ice has passed over. The pieces can be as big as boulders or as fine as sand grains or clay and are often all mixed together. The eastern limit of the ice in Herefordshire is marked by a ridge of moraine lying roughly north-south along the line of the A49.
After a couple of thousand years the ice lobe melted and shrank westwards, before expanding again leaving a new ridge of moraine in the Norton Canon area. This dammed a lake in the area of the present-day Sturts Nature Reserve.
Around 22,000 years ago, the ice lobe started to melt completely and retreat. Debris within the ice was dumped forming “hummocky” moraine. Today this forms the distinctive landscape of gentle bumps and hollows found in West Herefordshire. Most Ice Age Ponds are found within hollows in these areas.
The Ice Age Ponds Project is already making new discoveries about the ice and its moraines in western Herefordshire.