LIFE-ZONES IN THE BRITISH CARBONIFEROUS ROCKS. 233 
The bed ‘ 15. Shales’ was highly fossiliferous, yielding the following 
forms :— 
Orthoceras sp. Pterinopecten papyraceus, Calamites sp. 
Goniatites, indeterminable species of. Postdoniella levis (large). 
Resting on ‘18. Grit’ were numerous large ellipsoidal calcareous 
bullions, some of which measured 2 ft. 6in. and 1 ft. 6 in. along their major 
and minor axes respectively. Asa rule the bullions contained numerous 
goniatites, and in one of them was found a fine specimen of Acrolepis 
Hopkinst. 
In ‘17. Shales’ Posidoniella levis and Glyphioceras reticulatum were 
fairly abundant. 
From ‘ 21. Shales’ Glyphioceras reticulatwm was collected. 
‘25. Compact shale’ contained large Pterinopecten papyraceus and 
Posidoniella levis in great numbers. 
‘27. Micaceous shale’ contained Pterinopecten papyraceus, Posidoniella 
levis, Orthoceras sp., and Goniatites of indeterminable species. 
In the middle of ‘29. Shale’ was a layer containing Pterinopecten 
papyraceus. 
‘33. Shale’ contained Glyphioceras reticulatum. 
‘35. Shales with lenticles of grit’ were very fossiliferous ; Posidoniella 
levis, Pterinopecten papyraceus, Glyphioceras reticulatum, and Goniatite 
sp. were collected. 
‘41. Shale’ contained Calamites sp. 
‘43, Micaceous shale’ contained fragmentary plant remains. 
The upper trench had been similarly cut across R. Derwent, a short 
distance above the Abbey Farm, in measures higher in the series, where 
the shales were thinner and the grits were thicker and formed an 
increasing proportion of the strata. 
The succession revealed by these two trenches corresponds with the 
shales and sandstones towards the base of the eastern scarp of Mam Tor, 
near Castleton, Derbyshire. 
The difficulty in getting continuous sections of Pendleside shales, 
owing to their disturbed character and to the fact that they are commonly 
exposed at the bottom of valleys, has been frequently observed. Some 
light was thrown on the subject by the position of the beds in these 
trenches. Figs. 2 and 3 show the relation of these disturbances to the 
valley and hills, as seen in the lower trench, the same general features of 
which were to be observed in the upper trench also. 
The distance between the two trenches, measured in a straight line, is 
about 1# mile, and the strata forming the bed of the river are thrown 
into an anticlinal fold with subsidiary wrinklings in both instances. 
These foldings are shown in fig. 3 to be confined to the strata near the 
surface, which consist of the softer and more incoherent shales, whilst the 
hard and thick grit (No. 42 in fig. 1) may be observed to have resisted 
the crush movement and forms a fairly level floor to the excavation. 
An examination of the ground renders improbable the idea that both 
the trenches intersect the same anticline, and remembering that both 
sections occur at the bottom of deep and narrow valleys one is forced to 
regard the ‘ wrinkle’ and the valley itself as being related in some way 
a8 cause and effect. There can be no doubt that considerable ‘side- 
thrust’ would result from the weight of these hills, which naturally would 
make itself felt most on those beds forming the bottom of the valley, 
