GLACIAL MARKINGS IN THE EED MAEL. 



By a. II. Atkins, B.Sc. 



Ilcdil hrforc the Sncicti/ Jdnutdi/ '^Snl, 1S83. 



' For some time past the atteution of local fjeologists has hecii 

 directed to the marks of Glacial action in the IMidlaiid Countii^s. 

 Their efforts tend to prove that the traces of the Glacial epoch extend 

 as far south as Birmin^^ham at least, and that either a sheet of ice 

 covered this nei^hhourhood, or else a number of ice-covered islands 

 lay in the midst of an extensive Glacial sea. As is well known, the 

 most common traces of ice action consist otroches moutouuecs, acvatches 

 on the rocks, and boulder clay containing striated and polished pebbles 

 and boulders. The former evidences are scarcely possible near Bir- 

 mingham, where all the rocks are too soft to receive or retain such 

 markings. At the Eowley Hills, however, Dr. Crosskey has discovered 

 large blocks of basalt striated in a manner which points to the actiou 

 of ice. 



Of the latter traces — viz., Boulder Clay, etc. — the best section in 

 this locality is to be seen at California, near Harborue, w'here there is a 

 thick bed of tenacious clay, containing fragments of all sizes most 

 perfectly scratched and polished, which also show in which direc- 

 tion they have travelled, for among them may be found fragments of 

 basalt, limestone coal-shale, limestone, slate, and in fact almost ail 

 the rocks which occur in situ between here and North Wales. Patches 

 of a similar clay may be met with in other localities, as, for instance, 

 Washwood Heath and TysuU. In almost every case it is accompanied 

 aud interbedded with masses of Drift, and there seems no doubt that 

 these latter beds were deposited at about the same period. 



This paper, however, as the title intimates, bears more especially 

 on the traces found iu the Red Marl, the uppermost division of the 

 Trias formation. 



This bed extends southward from Birmingham to Warwick aud 

 Stratford, aud consists of marl iuterstratified with characteristic layers 

 of brown saudstoue aud white or grey shale. These bauds contain iu 

 abundance ripple markings, rain-drop impressious, aud pseudomorphs 

 of salt crystals, which, together with the beds of rock salt and 

 gypsum which occur in this formation, show that it was deposited in 

 a great continental salt lake, like the Dead Sea of the present era. 



The Boulder Clay is not, at first" sight, easily distinguishable from 

 the Red Marl, but a close iuvestigatiou will show that there is ofteu a 

 top layer of clay of very much better quality, commercially speaking, 

 than the Red Marl below ; a fact of which the brickma.kers of the district 

 are well aware. Mr. W. J. Harrison, F.G.S., first called attention to 

 a section at Small Heaih, where the white bands of the Red Marl were 



