218 MISS G. E. WATNEY AND MISS E. G. WELCH ON THE [May 191 I, 



a surface is obtained, the fossils in places are almost unrecognizable. 

 The complicated system of faulting shows that movements have 

 considerably affected the area ; the presence of felsite and lampro- 

 phyre dykes is also of interest. 



We have observed that the lowest Wenlock Beds invariably have 

 their fossils preserved in relief, and this is a distinctive feature of 

 these beds throughout the whole of the Cautley area. 



An ascendiug section shows a greater tendency towards flagginess 

 in the rock, and the introduction of pyrite in the form of abundant 

 tiny cubes causes the strata to weather to an ochreous colour. The 

 highest beds are characterized by irregular calcareous concretions, 

 varying from a few inches to a foot in diameter ; the banding- 

 is very marked, and the rocks weather to a light brown. 



On the north and west the Sally Beck and other faults bring the 

 Wenlock Beds against strata of their own age, or against the Brow- 

 gill and Ludlow ; but on the Bluecaster side there is a conformable 

 passage downwards into the Browgill Group. The general dip of 

 the beds is 30° north-north-westwards: they strike, therefore, across 

 the gills which run in a north-westerly and westerly direction ; 

 but, although sections are numerous, they are, with the exceptions 

 of those in Middle and Near Gills, never complete. As a rule, the 

 fossils occur in bands in the rock, or even along definite bedding- 

 planes. There seems to be no means, however, of distinguishing 

 between the fossiliferous and the unfossiliferous bands. 



It is from a study of the exposures in the Bluecaster gills and 

 their fauna that we have become convinced that the Wenlock Beds 

 of this area are divisible into four zones, namely : — 



(1) Zone of Cyrtograptus lundgreni. C 4 . 



(2) Zone of Cyrtograptus rigidus. C 3 . 



(3) Zone of Monogra ptus riceartonensis. C. 



(4) Zone of Cyrtograptus murohisotii. . C x . 



Bluecaster Gills: (i) Par Gill. 



The exposures in Far Gill are large and fairly fossiliferous ; but 

 the rocks are so highly cleaved that the fossils are almost obliterated, 

 or seen only as smudged impressions. The highly cleaved state 

 of the rocks may be due to the proximity of a fault on the north 

 of the gill. 



Cyrtograptus-murchisoni Zone (CJ. — Just above the old 

 road splintered blue flags crop out in the gill-bed, dipping at 36° 

 north-west by north. The fossils found were typical of the zone : 

 Cyrtograptus murcliisoni, Monograptus priodon, and Orilioceras 

 occur in abundance. Below the old road two felsite-dykes cross 

 the gill ; the rocks are baked by these, and for a distance of 

 100 yards no fossil is to be found. These beds presumably belong 

 to the zone of Monograptus riceartonensis. 



The rocks in the higher part of the gill break with greater ease 

 along the bedding-planes, and are ochre-stained. 



