402 STRATIGRAPHICAL GEOLOGY 



Clays with ^Egoceras capricornus, 130 feet. 



Shaly micaceous clays with Uptonia Jamesoni, 225 feet. 



Clays with Asteroceras oltusum, Oxynoticeras oxynotum, and 



Echioceras raricostatum, 100 feet. 



y Shales and limestones with Anetites Turneri and Arnioceras 



>-> t \ semicostatum, 66 feet. 



Shales and thin limestones, zone of Arietites BucTclandi, 113 



feet. 



Shales and thin limestones, Schlotheimia angulata, 30 feet. 

 Zone of Psiloceras planorbe below, but not accessible 



( ? 50 feet). 



Mr. R. H. Rastall has shown 8 that it is only at Blea Wyke on 

 the coast that a complete passage from Lias to Inferior Oolite is 

 seen. At other localities the ferruginous sands which form the 

 base of the latter (see p. 420) rest upon an eroded surface of the Lias 

 and usually upon some part of the commune zone. In many places 

 currents have cut channels in the Lias, and these are often filled 

 with sand at the base of which is a layer of pebbles and phosphatic 

 nodules. 



4. Cumberland, Ireland, and Scotland 



These areas may well be considered together, for there can be 

 no doubt that the Liassic Series was originally contimious across 

 the seas which now divide them. 



Lower Lias. It is interesting to find an outlier of Lias in the 

 Carlisle basin, because it confirms the view that the northern 

 Pennine Hills were not then in existence, but were part of the 

 Triassic plain which became first the floor of the Keuper Lake and 

 subsequently that of the Liassic Sea. It is believed, however, that 

 the Rhaetic Beds are absent, and that the zone of Psil. planorbe 

 rests unconformably on the Keuper marls. The whole country is 

 covered with glacial drift, so that there are few exposures, but a 

 boring near Great Orton passed through 210 feet of dark shales 

 with bands of limestone in the lower part. 



In Ireland the Lower Lias is found at intervals along the coast 

 of Antrim between the Trias and the Cretaceous rocks, but is 

 frequently cut out oy the overstep of the latter. The zone of 

 Pteria contorta is well developed, the lower part consisting of grey 

 shales and sandstones with fish remains, the middle of black shales 

 with the usual fossils, and the upper of grey shales with layers of 

 oolitic limestone, and the whole is about 80 feet thick. These 

 beds are succeeded by Lower Lias with the same lithological facies 

 as in England, but the series is cut off in or above the zone of 

 Echioceras semicostatum. 



The mapping of the Isle of Arran by the Geological Survey 



