Soil topochronosequences at Storbreen, Jotunheimen, Norway

The rate at which an undifferentiated pile of geologic materials becomes organized into a soil is unknown in most environments. To this end, we examined soil development and chemical weathering trends on four dated Holocene moraines and on adjacent 9000-yr-old sites at Storbreen glacial foreland in Norway. Our objective was to determine the influence of land surface age, elevation, and landscape position on soil properties in this alpine environment. Sampling sites on moraine crests and bases ranged in elevation from 1165 to 1465 m and in age from 70 to 250 yr old. The soils were mostly frigid or isofrigid, coarse textured, and poorly developed Cryorthents. However, there were differences between same-age soils at different elevations, same-elevation soils of differing ages, and soils from adjacent moraine crest-base pairs. Older and higher elevation soils tended to have more silt and clay, possibly due to eolian additions. Extractable Al and Fe, cation exchange capacity (CEC), organic C, and C/N ratio tended to increase with time, while pH, base saturation, and most extractable elements generally decreased with time. Extractable Mg, Al, Fe, K, P, and Cu tended to increase with elevation. Soils at moraine base locations were cooler and had more organic C than adjacent moraine crest soils. The rate of organic N accumulation initially is rapid, but diminished with time from 0.120 to 0.001 g cm(-2) yr(-1) on the 70- and 9000-yr-old surfaces, respectively. Organic C accumulation rates were greatest on the 250-yr-old surface, 0.31 g cm(-2) yr(-1), and slowest on the 9000-yr-old surface, 0.02 g cm(-2) yr(-1). Rates of organic C and N accumulation both increased with elevation. Primary minerals, quartz, mica, feldspar, and amphibole dominated soil mineralogy. Secondary minerals, in particular hydrobiotite, increased with age and elevation, thus revealing weathering trends. Despite generally poor soil development, we found detectable topochronosequence differences in soils and weathering in this young, cold environment.