€. LAPWOETH ON THE MOEEAT SEKIES. 255 



a very acute angle; and the lower zones of the Birkhill Shales, 

 wanting in the floor of the lateral gorge, come in visibly one by one 

 on the western side of the fault. 



The M.-gregarius zone seen in the burn is followed in the cliffs im- 

 mediately by the zone of hard thick-bedded black flags with Diplo- 

 graptus vesiculosus. Here, exactly as in our type section of the Main 

 Cliff, these flags form the most prominent portion of the slope, over- 

 hanging and protecting the subjacent and softer beds. The D. vesi- 

 culosus band is followed in turn by the zone of D. acuminatus, with 

 its shivery shales of greyish black, and the peculiar calcareous 

 brownish gingerbread-coloured band at its base, swarming with the 

 same exquisitely preserved fossils. 



Upon the drab line reposes the green-shale band, of about 6 feet 

 in thickness, that constitutes the upper portion of the D.-anceps zone 

 of the highest Hartfell Shales of the Main Cliff ; and next follows the 

 fossiliferous portion of the D.-anceps zone itself. The latter forms the 

 north-west wall of the upper part of the West Score, and is crushed 

 up in a sharp fold against the fault, which probably dies out a few 

 feet beyond. Not many of the fossils of the D.-anceps zone are pro- 

 curable from the smashed beds, but quite sufficient to show that 

 they are identical with those of its prototype in the Main Cliff. 



Crossing the line of fault, an apparent thickness of 60 or 70 feet 

 of barren green mudstone is passed over in the North Cliff and the 

 bed of the stream, a thickness it is very difficult to reconcile at first 

 sight with the 30 feet of the same rock as exposed in our typical 

 section. A careful attention to the lithological characters of the 

 beds, however, soon reveals the fact that this excessive thickness is 

 due to folding. Near its southern termination we recognize the 

 thin black fossiliferous line of the band, here repeated two or three 

 times. 



Next in order comes the thin-bedded slaty-shale zone (Pleuro- 

 graptus linearis), forming the highest subdivision of our Lower 

 Hartfell Shales, the line of junction between it and the very dif- 

 ferently coloured mudstones of the preceding zone forming a long 

 straight line up the face of the North Cliff. The beds of this zone 

 form a prominent portion of the summit, and yield all its fossils in 

 abundance. 



These beds are succeeded in the cliff by the D.- Clingani zone of 

 hard black slaty shales. At the top of the cliff they are beautifully 

 exhibited (but in a highly- contorted condition) near the head of the 

 East Score, and are prolonged in some rugged bosses of black rock 

 that protrude through the turf much further to the north. The 

 distribution of their included fossils, Dicellograptus Forchhammeri, D. 

 caduceus, Dicranograptus ramosus, D. Clingani, &c, makes it certain 

 that these convoluted beds are portions of one and the same thin 

 zone. 



Up to this point, then, it is perfectly clear that the succession 

 among the beds in the North Cliff, from the greywackcs of the falls 

 to the Lower Hartfell Shales, is identical in every respect with that 

 in our typical section of the Main Cliff. Here, however, the strata 



