Carboniferous rocks are now most extensively preserved in central Scotland, the Borders and the offshore areas east of Scotland. Preservation is patchy and successions are generally thin and incomplete in the offshore areas west of Scotland, the Highlands and Southern Uplands, which all tended to remain positive throughout much of the period. However, Carboniferous cover was formerly much more extensive than at present, as demonstrated by a series of isolated outliers with attenuated successions in the Western Highlands and Islands and the Southern Uplands. Most of the cover in these areas was stripped off during the latest Carboniferous uplift and erosion. The basal junction with the Upper Devonian is arbitrary, because it is drawn at the first appearance of calcareous soil profiles (calcretes) within an unfossiliferous fluvial and aeolian succession, but it is usually conformable and coincides with a widespread change to a slightly wetter climate (Paterson et al. 1990; and Chapter 8). Progressive overlap took place at various horizons including the early Carboniferous, the base of the Namurian and the Early Westphalian. Figure 9.1 shows Scotland and the adjacent offshore areas, with onshore Carboniferous outcrops, major structures and the principal localities mentioned in the text, and Figure 9.2shows the onshore outcrops in central and southern Scotland in greater detail. Preserved Carboniferous strata tend to be thin in the west and thickest in the east, with thickening in local basins (Browne et al. 1985). Figure 9.3 shows the chrono- and lithostratigraphical divisions