600 BEPOET— 1889. 



The basaltic dykes are of two ages ; some seem to be of about tlie same age as 

 tbe Whin Sill. Indeed, small local ' sills ' seem sometimes to have branched out from 

 the dj'kes ; and some dykes are apparently pre-permian. Other dykes are certainly 

 much later, and no doubt belong to the great Tertiary volcanic outburst, the general 

 history of which has been lately written by the Director-General of the Geological 

 Survey. Some of the dykes which preserve so long a course through the country 

 (such as the Cleveland and the Acklington dykes) belong to this later series. 



The glacial and other drift deposits ha\'e throughout been mapped by the 

 Survey on the six-inch scale ; ice-marks and other phenomena connected with the 

 glaciation of the district being also recorded. 



The higher summits of the Cheviots, and the high areas of carboniferous rocks 

 to the south-west of these, are believed by Mr. Clough to have acted as independent 

 centres of glaciation, and never to have been overridden by any general ice-sheet ; 

 but all the rest of Northumberland has been covered by an ice-sheet, coming from 

 the west on the south side of the Cheviots, and from the north and north-west on 

 the north and east of the Cheviots. Tbe glacial markings and other phenomena 

 connected with the drift give evidence of this. In the county of Durham also 

 there is a considerable area near Teesdale and Weardale that seems to have acted 

 as an independent centre, 



4. On Concurrent Faulting and Deposit in Carboniferous Times in Graven, 

 Yorkshire, loith a Note on Carboniferous Beefs. By R. H. Tiddeman, 

 M.A., F.G.8. 



I propose to give briefly, in abstract only, some of the conclusions to which I 

 have been drawn by a study of the rocks on both sides of the Craven fault in the 

 district about Settle, Skipton, and Clitheroe during the progress of the Geological 

 Survey, and these remarks are offered by permission of the Director-General. 



The following subjects will be treated with all possible brevity: — 



I. The range of the main branciies of the Craven fault. 



II. The nature, thicknesses, and extent of the rocks — 



(i.) North of the faults ; 

 (ii.) South of the same. 



III. The questions suggested by the phenomena and the conclusions arrived at. 



IV. A note on the existence of Carboniferous reefs in the district, their structure 

 and probable mode of growth. 



I. The Craven faults are well known to geologists, and have been treated of in 

 the works of Sedgwick, John Phillips, and many others. The portions to which I 

 shall allude in this paper extend from lugieton, in the Lune basin, to beyond 

 Grassington, in that of the Wharfe. 



There are three principal lines of fault along this portion : — 



(«) The northern runs from north of Ingleton and Clapham by Feizor, Stain- 

 forth in the Kibble Valley, Malham Tarn, Threshtield, to, and perhaps beyond, 

 Pately Bridge. 



(b) The Mid-Craven fault runs through Ingleton, only a short distance south of 

 the other, and traverses Clapham, Austwick, thence below the picturesque Giggles- 

 wick Scars through the village of that name and Settle to Malham Cove and Gordale. 



(c) A third fault, the South Craven fault, branches off from this near Settle, 

 and, taking a more southerly course, passes by Scaleber Force and Holmes Gill 

 Green to Gargrave and Skipton. 



The greatest apparent depth of faulting is at Ingleton, where the Coal- 

 measures are thrown down on a level with Silurian rocks; but as we follow 

 the fractures to the east and south-east they branch off and become more in number 

 and less in importance. 



There are other minor faults, but those with which we are now chiefly 

 concerned and which have caused the greatest results are the two first above 

 mentioned. The effect of them is to throw down on the south and south-west. 



