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Autochthonous blockfield mantles may indicate alpine surfaces that have not been glacially eroded. These surfaces may therefore serve as markers against which to determine Quaternary erosion volumes in adjacent glacially eroded sectors. To explore these potential utilities, chemical weathering features, erosion rates, and regolith residence durations of mountain blockfields are investigated in the northern Swedish Scandes. This is done, firstly, by assessing the intensity of regolith chemical weathering along altitudinal transects descending from three blockfield-mantled summits. Clay / silt ratios, secondary mineral assemblages, and imaging of chemical etching of primary mineral grains in fine matrix are each used for this purpose. Secondly, erosion rates and regolith residence durations of two of the summits are inferred from concentrations of in situ-produced cosmogenic Be-10 and Al-26 in quartz at the blockfield surfaces. An interpretative model is adopted that includes temporal variations in nuclide production rates through surface burial by glacial ice and glacial isostasy-induced elevation changes of the blockfield surfaces. Together, our data indicate that these blockfields are not derived from remnants of intensely weathered Neogene weathering profiles, as is commonly considered. Evidence for this interpretation includes minor chemical weathering in each of the three examined blockfields, despite consistent variability according to slope position. In addition, average erosion rates of similar to 16.2 and similar to 6.7 mm ka(-1), calculated for the two blockfield-mantled summits, are low but of sufficient magnitude to remove present blockfield mantles, of up to a few metres in thickness, within a late Quaternary time frame. Hence, blockfield mantles appear to be replenished by regolith formation through, primarily physical, weathering processes that have operated during the Quaternary. The persistence of autochthonous blockfields over multiple glacial-inter

Relict non-glacial surfaces occur within many formerly glaciated landscapes and contain important information on past surface processes and long-term landscape evolution. While cosmogenic dating has confirmed the antiquity of relict non-glacial surfaces, the processes that contribute to their evolution and, consequently, the time scales over which they develop remain poorly understood. Of particular importance is the possibility that relict non-glacial surfaces may provide geomorphic markers for the reconstruction of preglacial landscapes, which would allow subsequent glacial erosion to be quantified. Furthermore, relict non-glacial surfaces may also hold information on preglacial and interglacial environmental conditions. An investigation of relict non-glacial surfaces was undertaken through remote sensing, mapping and analysis of surfaces in a GIS, and regolith studies involving cosmogenic dating-, grain size-, X-ray diffraction-, and X-ray fluorescence analyses. On the basis of these on-going studies, we show that depending on spatial variables such as bedrock lithology, slope, regolith thickness, and the abundance of fine matrix and water some surfaces are denuding very slowly, while others display more rapid denudation. High spatial variability in denudation rates results in changing surface morphologies over time. Rather than being static preglacial remnants, relict non-glacial surfaces are dynamic features that have evolved during the Quaternary. While reconstructions of preglacial landscapes and subsequent quantifications of glacial erosion from relict non-glacial surfaces remain valid, the Quaternary evolution of these surfaces should also be considered.

The prevailing paradigm for cold-climate in situ blockfields is that they are remnants of Neogene deep weathering profiles. This opinion is frequently based on the presence of large quantities of interstitial silt and clay and/or the presence of clay minerals, such as gibbsite and kaolinite. Using in situ-produced cosmogenic isotopes 10Be and 26Al, XRD, and XRF to study blockfield regolith in the northern Swedish mountains, we challenge this paradigm. Incorporating surface burial by ice sheets, the isostatic response to ice sheet loading and unloading, and subaerial surface erosion, the cosmogenic data indicate that the regolith has been accumulating nuclides for up to 464.5 ka. The ubiquitous presence of chlorite makes it impossible to distinguish kaolinite according to standard XRD techniques. However, gibbsite is present in glacial till in addition to wet- location blockfield regolith. Coupled with the ubiquitous presence of poorly crystallized hydroxides, vermiculization in wet-locations, and an absence of smectite, incipient chemical weathering is indicated. Furthermore, XRF data indicate dominance of the interstitial fine matrix by a foreign component, likely of aeolian origin. All of our observations can be explained by processes operating within the Quaternary timeframe. Because we do not need to appeal to Neogene deep weathering to account for the characteristics of blockfields in the northern Swedish mountains we conclude that these blockfields may have Quaternary origins.