Stonehenge and the Ice Age: Knock and lochan terrain -- the Teifi Pools again

In a post the other day about the Teifi Pools area, I showed some shots of the landscape and described it as typical of areas of areal scouring close to -- or beneath -- the ice shed of either an ice sheet or an ice cap. In the case of the Teifi Pools the ice shed during the Devensisn glaciation -- and probably others as well -- migrated back and forth over a distance of maybe 20 miles, but the map below (by7 Henry Patton and others) shows its approximate position:

The white-coloured "spine" down the centre of the ice cap shows the highest part of the ice dome, possibly the area of lowest basal ice temperatures (cold or polar ice rather than temperate ice) and the area of most sluggish ice movement and hence lowest erosional rates. However, because conditions were never static, and as the ice shed moved to east or west, there WAS some erosion, entrainment and debris removal, albeit on a less organized scale than in the flanking areas where streaming was increasing and where eventually the ice discharge was through distinct glacially eroded channels. We are talking about the area between Tragaron and Rhayader.

The landscape in this ice-shed area is often referred to as "Knock and Lochan" topography, after Prof David Linton who studied certain glaciated landscapes in the western parts of Scotland.

There's a good description here:

http://www.landforms.eu/shetland/Knock%20and%20lochan.htm

Let's just look at the landscape again:

On the lower photo the Teifi Pools are top left. You can see that there is quite a strong structural control here, which makes me rather reluctant to refer to this as a "glacially streamlined" landscape. But on the other hand it is clearly scoured, with the eroded rocky ridges standing proud, and the eroded softer rock depressions filled -- in some cases -- by lakes.

When he first used the term "knock and lochan terrain" I don't think Linton had any idea of just how widespread it is across the surface of Planet Earth. Many millions of hectares are to be seen across all landscapes affected in the past by ice sheets -- in Greenland, North America, Arctic Russia, Scandinavia, Antarctica -- and in many other areas such as Iceland, the highlands of Asia, and parts of South America where smaller ice caps have been based on plateau surfaces. Here are a few examples(note that the scales vary):