CalcretesCalcrete and silcretesSilcrete are the most widely encountered 'rocks' in the Kalahari sandveldSandveld that covers much of BotswanaBotswana. This chapter presents the first holistic overview of current knowledge about these duricrustsDuricrust at a national scaleScale. It does so by considering the distribution, classification, macromorphology, geochemistryGeochemistry and mineralogy of each duricrust type in turn, alongside various models used to explain their formationFormation. The chapter then reviews our understanding of a variant of duricrust encountered more in the Botswana Kalahari than anywhere else in the world—the silcrete–calcrete intergrade duricrust. The chapter concludes with a summary of knowledge about the age of duricrustsDuricrust in Botswana before pointing to potential directions for future research.

Previous reconstructions of the glacial history of the last Fennoscandian Ice sheet (FIS) in northwest Arctic Russia are limited in scope owing to a lack of empirical geomorphological and chronological data. As a result, previous reconstructions suggest the Kola Peninsula was glaciated by either the FIS, the Ponoy Ice Cap, or the Kara Sea Ice Sheet. Utilising new databases of over 245,000 mapped glacial landforms and 209 numerical ages, we present a new time-slice reconstruction of Late Weichselian (c. 40-10 ka) FIS glaciation on the Kola Peninsula and Russian Lapland. Subglacial bedforms are used to reconstruct ice flow geometry in the region. The relative age sequence of events demonstrates an evolving ice sheet configuration, including ice sheet build-up and retreat stages, and evidence of ice streaming. Moraines and meltwater landforms are used to reconstruct ice margin positions in the region. The Kola Interlobate Complex, stretching almost 400 km, is likely to be a time-transgressive landform assemblage, which formed at an east- and northeast-migrating junction between the warm-based White Sea lobe and cold-based ice on the Kola Peninsula, probably before the Last Glacial Maximum. Reconstructed retreat ice margin positions indicate that FIS retreat is characterised by thinning, resulting in a lobate ice margin. This new reconstruction provides a framework into which sedimentary and chronological reconstructions can be contrasted and compared. This research also provides crucial empirical data for validating numerical model simulations of the FIS, which in turn will further our understanding of ice sheet dynamics in other Arctic, Antarctic, and Alpine regions.

[RC2] Regarding objective one [of the paper: ‘provide a global state-of-the-art review of the development and application of the index approach in historical climate reconstruction’], the review is exhaustive reflecting most of the previous work based on ordinal indices that consider the departure from normality as the main criterion to produce an anomaly scale with several levels of intensity. However, references to other ap-

Linear sand dunes in the southwest Kalahari dunefield have been widely observed to change pattern, size and orientation in the vicinity of river valleys, yet few explanations for this change have been put forward. This paper identifies and describes four main associations between dunes and valleys which occur in the southwest Kalahari: (i) dunes which adjoin the valley on both sides with no discernible change in pattern or orientation; (ii) dunes which adjoin the valley and change pattern; (iii) dunes which adjoin the upwind valley flank but not the downwind side; (iv) dune-free zones on both sides of the valley. The two main factors which influence the evolution of these associations are identified as the effect of the valley upon sediment supply and the effect of the valley upon wind regime. Our current state of knowledge about the potential geomorphological effects of these two variables is evaluated with reference to each association described.