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Sunday, 6 December 2009

Lessons from Jameson Land?



Jameson Land, East Greenland. On the satellite image, Jameson Land is the large unglaciated area to the east of the broad Scoresby Sund -- which carried the ice from a number of the East Greenland Fjords. The undulating landscape of central Jameson Land is very different from that of the "fjordland" to the west and north.

Ah - happy days! I walked across part of this area and worked here in 1962. Been pondering a bit on how we might find parallels between this area and Salisbury Plain -- a lot of geomorphology is done by analogy, in which we seek guidance to what happened in one landscape by reference to what can be observed elsewhere, in similar terrain or where glaciological circumstances might have been similar.

Jameson Land might give us clues -- because instead of seeing evidence here of streaming ice and deep erosion, we appear to have a landscape which has been effectively protected by stagnant or sluggish cold-based ice. Lena Hakansson, who has studied this area, says that: "... local ice with limited erosion potential covered and shielded large areas for substantial periods of the last glacial cycle." Local ice -- that's interesting, and maybe something that gives us a guide to what might have happened over the Mendips, Dartmoor and Exmoor. But there are erratics and some exposures of till in Jameson Land -- these appear to be much older.

There are plenty of erratics on Salisbury Plain, as shown in earlier posts on this blog. Till is usually observed in river cuttings or road excavations. But because Salisbury Plain is made of chalk, the effects of fluvial erosion are very limited. What we have are coombes or dry valleys, but few exposures or cuttings to tell us whether there are any thick sediments present, and how they may be distributed. We know about the "clay-with-flints" and occasional river terraces made of gravels, but otherwise there appear to be no records of anything that might be referred to as unequivocal "till" or boulder clay. I wonder what's lurking beneath the surface, waiting to be discovered?

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