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A Mid-Carboniferous Boulder-bed near Settle

Published online by Cambridge University Press:  01 May 2009

E. E. L. Dixon  and
R. G. S. Hudson
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Extract

(1) The blocks of limestone in the Bowland Shales of School Share include a variety of rock-types of northern (Yoredale) facies and come from several beds near the Orionastraea Band of the Upper Viséan.

(2) They are a local accumulation at the local base of the Namurian (Upper Bowland Shales; zone of Eutnorphoceras pseudobilingue, E1 and rest, with evidence of some slight erosion, on one of the highest horizons of the Viséan (Lower Bowland Shales; zone of Goniatites spiralis, P2). Their horizon, therefore, is that of the mid-Carboniferous unconformity of Settle and elsewhere.

(3) They mark a comparatively small faunal hiatus (between the newsomi-meslerianum level immediately below and the C. malhamense level above).

(4) Their separation from the parent rocks and their assemblage are not due to tectonic causes. On the other hand, their great size points to some unusual form of transport.

(5) As they occur in a shale series near the Craven Faults they may legitimately be explained as the result of land-slips down s muddy slope from a limestone cliff, probably a fault-scarp raised by the mid-Carboniferous earth-movement.

(6) The circumstances recall those attending the Lower Palaeozoic conglomerates of Quebec. A recent explanation ascribes these to landslips caused by earthquakes from submarine fault-scarps. The School Share landslip may well have been caused by earthquakes, and the scarp from which the blocks were derived may have been essentially submarine.

Type
Original Articles
Information
Geological Magazine , Volume 68 , Issue 2 , February 1931 , pp. 81 - 92
Copyright
Copyright © Cambridge University Press 1931

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References

page 81 note 1 The Namurian as redefined in the Compte Rendu, Congrès de Stratigraphie carbonifère, Heerlen, 1927 [Liége, 1928], occurs between the Dinantian and Westphalian and roughly corresponds to the Millistone Grit of Great Britain. At that conference the subzone of Goniatites spiralis was provisionally taken as the junction between the Dinantian and Namurian; in this paper the division is more definitely made in that it is drawn between the subzone of G. spiralis (P2) and the zone of Eumorphoceras pseudobilingue (E1). The definition of the upper limit of the Namurian, usually in Great Britain placed at the top of the Reticuloceras reticulatum Zone (R2), does not concern us. The name “Lancastrian” is dropped.

page 82 note 1 For details of the structure of the district see Hudson, R. G. S., “The Carboniferous of the Craven Reef Belt; The Namurian Unconformity at Scaleber near Settle”: Proc. Geol. Assoc., xli, 1930, 290–322.CrossRefGoogle Scholar

page 83 note 1 “On the Limestone Knolls in the Craven District of Yorkshire and elsewhere”: Quart. Jour. Geol. Soc., lv, 1899, 347, fig. 12.Google Scholar

page 83 note 2 “The Lower Carboniferous Succession in the Settle District”: Quart. Jour. Geol. Soc., lxxx, 1924, 230–2.Google Scholar

page 84 note 1 For the photographs reproduced in Pl. V we are indebted to Mr. J. Ranson.

page 85 note 1 Chapman, F. has shown that “Saccammina carteri Brady” is synonymous with S. fusuliniformis (M'Coy) (Ann. May. Nat. Hist., 1898, 215–18).Google Scholar

page 87 note 1 Booker, K. M. and Hudson, R. G. S., “The Carboniferous Sequence of the Craven Lowlands South of the Reef Limestones of Cracoe”: Proc. York. Geol. Soc., xx, 1926, 429–430.Google Scholar

page 87 note 2 Hudson, R. G. S., “The Carboniferous of the Craven Reef Belt: The Namurian Unconformity at Scaleber, near Settle”: op. cit., 306–8.Google Scholar

page 88 note 1 The authors thank Mr. W. S. Bisat for identifying all the goniatites found at School Share and Mr. W. B. R. King for indicating the bullion containing these particular forms.

page 89 note 1 R. G. S. Hudson, op. cit., 308–12.

page 89 note 2 See Dixon, E. E. L. in “The Geology of the Whitehaven District”: Proc. Geol. Assoc., xxxvi, 1925, 53.Google Scholar

page 89 note 3 Bisat, W. S., Geol. Mag., LXV, 1928, 43;Google Scholar and Compte Rendu, Congrès de Stratigraphie Carbonifère, Heerlen, 1927 [Liége, 1928], 125.Google Scholar

page 89 note 4 Communicated by Mr. E. W. J. Moore.

page 90 note 1 “Breccias,” Geol. Mag., LXV, 1928, 100.Google Scholar

page 90 note 2 R. G. S. Hudson, op. cit., 315–17.

page 91 note 1 “Palaeozoic Submarine Landslips near Quebec City”: Jour. Geol., xxxvi, 1928, 577–614.Google Scholar