AT GREAT CEOSBY, LANCASHIRE. 



455 



It was not until several examinations were made that I was able 

 to discover any striations on the imbedded sandstone. At last I 

 detected them on a block measuring 4 ft. x 2 ft. 10 in. x 1 ft. 9 in. 

 in extreme dimensions. On washing the marl}- clay off the face, 

 very good parallel groovings were disclosed, running along the plane 

 of bedding and the longer axis. With this clue I soon saw that 

 the undersides of most of the stones were polished smooth, and others 

 irreffularlv scratched. 



Section at Moiuhrey Brich and Tile WorJcs, Great Croshy. 



a, a. Grey shaly Keuper marl. h. Hard band in Keuper marl broken off at h\ 

 b", b". Fragments of hard band, b, scattered through and imbedded in 

 the " kneaded-up " marl, c, c. " Kneaded-up " marl, that is the Keuper 

 marl or shale, worked-up into a grey clay, d, d. Blocks of sandstone, 

 some fine-grained and strong, others coarser in grain and often smoothed 

 and striated, in one instance strongly fluted, e. Half-imbedded block 

 /. Low-level Boulder-clay (marine), containing far-travelled erratics and 

 broken marine shells (brown in colour). 



Specimens of the undisturbed marl and the kneaded-up marl 

 were sent to Mr. David Eobertson, F.G.S., who kindly examined 

 them microscopically. Xo organisms were found in either, and they 

 were practically of the same constitution. jSTo far-travelled erratics, 

 nor any stones or material that could not be referred to the Keuper 

 formation could be found in the kneaded-up marl. Even the half- 

 imbedded stones were, in all cases that I have seen, Keuper sand- 

 stones. The true erratics are confined to the overlying Low-level 

 Boulder-clay. This clay is so distinctive a deposit that it is only 

 necessary to say that here as elsewhere it contains fragments of 

 marine shells, and is undoubtedly of aqueous and marine origin. 



Imjjortance of the Discovery. — The evidence of these disturbed 

 shales is of importance taken in connexion with the prevalence in 

 South-west Lancashire and Cheshire of glacial markings and 

 smoothed rocks. 



At the present moment (March 1885) is to be seen a very fine 

 example of polished and striated rock at Flaybrick Hill, Birkenhead, 

 Cheshire, a veritable roche moutonnee which has only just been bared 

 of its covering of Low-level Boulder-clay. 



It has, however, been a moot point with local geologists whether 

 these markings are due to land- or floating ice. I have myself 

 always considered that the weight of evidence preponderated in 

 favour of land-ice, though there are some facts apparently rrrecon- 



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