BLOCKFIELDS, OLD OR NEW - EVIDENCE AND IMPLICATIONS FROM SOME PLATEAUS IN NORTHERN NORWAY

Evidence is presented from investigations on plateau-top blockfields i n still-glaciated regions of north Norway. Pits dug into these blockfi elds typically show profile depths > 0.5 m, and sometimes in excess of 1 m. Analysis of fines shows enrichment in the silt and clay sized fr action, suggestive of prolonged chemical weathering. Chemical alterati on of parent material is supported by XRD analysis, which identifies a number of clay minerals present in blockfield samples. A chemical wea thering origin suggests that these plateau-top blockfields are feature s which have considerable longevity in the landscape and have been for ming since perhaps Tertiary times. The original weathering profiles ha ve been destroyed by frost heaving mechanisms. Protection of the block field by cold-based ice occurred during periods of glacial coverage.