The present paper records an attempt to establish a faunal sequence in the Carboniferous deposits in the Clitheroe district of North-East Lancashire. The area dealt with forms a small part of the large spread of Carboniferous strata lying south of the Craven Faults. The rocks of this region have been thrown into a series of more or less parallel folds with a general trend from east-north-east to west-south-west. The most important upfold is the Clitheroe Anticline, dissected by the Ribble, which runs west-south-westwards in the neighbourhood of Clitheroe, exposing the Carboniferous Limestone along the axis. On the north-western flank the synclinal Millstone-Grit hills of Longridge, Waddington, and Grindleton connect the Clitheroe Anticline with that of Slaidburn, in Bowland; while on the south-east there is a continuous succession through the grits of the Pendle Range to the Coal Measures of the Burnley Basin. The ground which has been mapped in detail forms that portion of the south-eastern limb of the Clitheroe Anticline which is included between the Twiston and Clitheroe Faults, along with most of the scarp-face of Pendle Hill below the Pendle Top Grit. Two small patches occur on the Yorkshire side of the county boundary. The low ground between the Ribble and Pendle Hill is occupied by the Clitheroe Limestone and the overlying ‘Shales-with-Limestone’ or Worston Shale Series. The upper part of the Clitheroe Limestone contains some of the typical reef-knolls which rise abruptly above the general level of the ground. One of these, Worsaw Hill, attains a height
I. Introduction The district which forms the subject of this paper covers an area of about 30 square miles in north-western Yorkshire, and comprises the north-eastern part of the region known as “Bolland” or “Bowland”. It lies almost entirely within the valley of the Hodder, a tributary of the Ribble, but the water-shed is crossed in the north-east, where the streams flow directly into the Ribble. The reservoir recently constructed by the Fylde Water Board is situated within the area, this part of the ground having been examined before submergence. The area is bounded on the north and west by the grit hills of Bowland Forest, which rise to altitudes of from 1400 to 1800 feet, and on the south-east by the grits of Easington, Newton, and Waddington Fells. The steep hillsides below the grit escarpments are occupied by the Bowland Shales, whilst the lower ground is usually Carboniferous Limestone with its associated shales; the harder rock sometimes forms prominent features, of which the more notable are knolls of reef-limestone. The stratigraphical sequence is as shown on the diagram (Pl. XXIV). It varies in detail from place to place as a result of facies changes and non-sequences, but is similar in a general way to that in the type area of Clitheroe-Pendle to the south-south-east. Figure 1 illustrates the variation in thickness and the positions of the non-sequences in different localities within the area to be described (Pendle being included for comparison). Bolland is noted geologically by reason of the
Summary The reef-knolls discussed in particular are Crow Hill, Worsaw, Gerna, Sykes and Twiston, all of which lie on the south-eastern limb of the Clitheroe anticline. It is shown that along the eastern side of Worsaw Hill the reef-limestone accumulated at high angles to the horizontal and at depths varying from sea-level down to 400 feet or more below, on a slope running perpendicular to the present strike of the surrounding beds. Shales and thin-bedded limestones were deposited between the reefs and contemporaneously with them on a sinking sea-floor. The larger knolls are considered to be the exposed parts of reefs which were originally ridge-like and ran parallel to the north-west and south-east fault lines and perpendicular to the later main orogenic axes. Some of the reefs may have been several miles in length, but their width rarely exceeded half a mile. Reef sedimentation was followed by uplift which resulted in erosion along the flanks of the reefs and a deepening of the depressions between them. The succeeding Worst on Shales were thus deposited on an uneven surface which resulted primarily from original irregularities of sedimentation but which was modified by subsequent earth-movement. I. Introduction In 1926, in describing the Lower Carboniferous succession of the Clitheroe-Pendle area, I adduced evidence supporting Tiddeman's theory (1900, and Kendall and Wroot 1924, p. 92) of the origin of the reef.knolls. It was argued that the stratigraphy could only be satisfactorily interpreted on the assumption that the limestone hills lying between the villages of
Growth and variation in a single species from a thin bed at one locality are examined statistically. The different dimensions are shown to be allometrically related both to each other and to the volume of the shell. It is argued that total width is the best measure of age of the individual and it is shown that at a certain width there is a break in the continuity of growth of the length and thickness.
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