The Ochil Fault, one of the most prominent tectonic features in the Midland Valley of Scotland, juxtaposes Lower Devonian volcanic rocks against late Westphalian strata, implying a possible vertical displacement of up to 4 km. The Kincardine Basin in its hanging-wall, although actively subsiding during the greater part of the Silesian, trends generally N–S, perpendicular to the Ochil Fault, and its Silesian sedimentary record shows little sign of tectonic control by that fault. It is proposed that the Ochil Fault was initiated, possibly as a sinistral strike-slip feature, in the Devonian, but acted as a sidewall fault during the early evolution of the Kincardine Basin, attributed to extension on a hypothetical pre-Brigantian fault along the Bo'ness Line on the east side of the basin until late Namurian times, when active extension ceased. Both faults were probably buried during late Namurian and Westphalian times. Reactivation of the Ochil Fault during end-Carboniferous N–S extension, dated by quartz-dolerite emplacement, was responsible for probably at least 2 km displacement. including the presently visible footwall uplift. It is suggested that the hanging wall may have contained a Permian basin, now removed.

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SUMMARY The quantitative relationships between stratigraphical variables from a succession of coal‐bearing cycles deposited in a subsiding basin have been investigated using principal component‐ and factor analysis, in an attempt to reveal simple relationships undetected by conventional qualitative methods. Knowledge of such relationships will undoubtedly be useful in future computer simulation studies of cyclical sedimentation. Principal component analysis and factor analysis yield similar results, which confirm and amplify those of the trend surface analysis described in Read and Dean (1967).

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This detailed quantitative basin analysis of fluvial deposits in a subsiding Namurian structural basin is aimed at discovering underlying statistical relationships between numbers of fluvial cycles, bulk lithological composition and net subsidence which could be used as a background to future sophisticated computer simulation experiments and would also facilitate comparison with other ancient basins. The succession studied lies between two widespread marine bands, one of Arnsbergian (E2) and one of Kinderscoutian (R1) age, and is dominated by upward‐fining cycles: 94% of the semi‐cycles containing sand, here termed grain‐size cycles, are upward‐fining and the ratio of fine members (mudstone+siltstone) to coarse members ranges from 0·23 to 5·0. Trend‐surface analysis reveals basement structures, which influenced sedimentation, including a Caledonoid graben. Correlation coefficient values and results of principal component analysis demonstrate that the numbers of rooty horizons and grain‐size cycles, together with the total thicknesses of sandstone and of mudstone+siltstone, all tend significantly towards a linear relationship with the total thickness of strata and hence net subsidence. The average thickness of grain‐size cycles tends towards an inverse linear relationship with net subsidence. This probably reflects the presence of stacked, relatively thin, channel‐fills within persistent channel belts. These belts tend to be localized in the areas of greatest subsidence within the basin and follow courses basically similar to channels already discovered in the underlying deltaic sediments. The highest concentrations of mudstone+siltstone tend to lie on the flanks of the basin, but high local sand concentrations found at points on the margin where channels entered the basin from the NW and NE and left to the SW, effectively disrupt any significant relationship between net subsidence and the proportion of sand. Coal has been selectively preserved on the flanks of the basin and the number of rooty horizons is greatest in an area of low subsidence which lay somewhat remote from the main channel belts.