Hughes — Geology of the Lake District. 353 



very like wliat have sometimes been called ash-beds. Some of these 

 beds cross Crummach Lane just north of Norber Brow. One is 

 seen in the stream close to the Dam House Bridge. The series rolls 

 over, and several such beds are seen dipping to the south, near Jop 

 Kidding, Woodend, Staindale, etc. Below them the slates become 

 more flaggy (B. 6. 3) ; have often long bands of concretions packed 

 parallel to the cleavage, so as to make it very difficult in small 

 sections to make out the bedding. They are well seen on Norber 

 Brow and under the Limestone cliff of Norber, in both of which 

 localities I found several specimens of Trinucleus. These beds pass 

 down into Coniston Limestone, which may be seen near Wharfe 

 Mill Dam, up Wharfe Gill Dyke, etc. 



Thus it will be seen that the flags of Horton, in Eibblesdale, lie 

 in a synclinal, the axis of which slopes to the east-south-east; and so 

 in the Crummack valley, we have only the lower part of the flags 

 (A.c. 1) preserved in the hollow of the grits (A.c. 2), while, in 

 the Horton valley, we have the whole of the flags, and at its east 

 end even part of the grits above the flags (A.&. 4), preserved in their 

 then deeper trough. 



Two anticlinals, also with their axes sloping to the east-south- 

 east, bring up the lower group (B) on the north and south of this 

 synclinal. 



Along the northern anticlinal, the grit A.c. 2 (which is a more 

 marked bed than A.c. 3), is close upon the Coniston Limestone B.&. ; 

 along the southern anticlinal it is separated from the limestone by 

 a very considerable thickness of slates and shales, etc., with Lower 

 Silurian fossils. 



Thus A appears to rest upon different beds of the underlying 

 group B. 



Also the base of A is sometimes a conglomerate made up of frag- 

 ments of the older series B. 



That is to say A rests unconformably upon B. 



Such are the stratigraphical relations of the rocks in the district 

 under notice. From these data I have constructed a Vertical Section 

 (IV.), to which I shall refer by index letters and numbers, in offer- 

 ing a few remarks upon the lithological character and paleontology. 



I have avoided giving names to the subdivisions, as I feel that 

 names derived from locality can probably be more conveniently 

 found in the typical region to the north and west, and that names 

 from characteristic fossils are not likely to hold good over large 

 areas, as all A, with which I have chiefly to do, is so undoubtedly 

 one group, that where similar conditions of sea bottom recurred, we 

 must expect to find that the same creatures were there or there- 

 abouts, ready to migrate and re-migrate to suitable areas. Probably, 

 also, most of the divisions will fit in with local names, already used 

 by Professor Sedgwick, such as Ireleth Slates, Brathay Flags, etc. 



When the fossils, collected by Mr. Gibbs and myself, have been 

 arranged and determined by Mr. Etheridge, I hope to offer larger 

 and more trustworthy lists. 

 . B.C. Green Slates. — These are the green slates and porphyry of 



VOL. IV. NO. xxxviii. 23 



