Geology Reference
In-Depth Information
Surface
Slumped material
OSL age:
~30 ka
OSL age:
~17 ka
3 m
3
0
Figure 12.11.
Field sketches of Late-Pleistocene thermokarst structures. (A) and (B) are from the
Pine Barrens, Southern New Jersey, Eastern USA. (A) Sketch of the sediment-pot illustrated in
Figure 12.8A. (B) OSL dating of a sediment-pot penetrated by a sand-wedge cast indicates a mid-
Wisconsinan period of thermokarst activity followed by a late-Wisconsinan period of permafrost
aggradation (frost-fi ssure formation). From French et al. (2005). (C) Sedimentary structures
described as “barrel-shaped macropolygons with river gravels,” Hungary. From Pecsi (1964). (D)
Pleistocene “ice wedges and kettles” in Cretaceous marl, Czechoslovakia. From Sekyra (1956).
Reproduced by permission of John Wiley & Sons Ltd.
