IN THE DEIFT NEAR FERRYHILL. 



291 



the west, as the photograph shows, it becomes intermingled 

 with some of the yellow sand which overlies it, beyond which 

 its place is taken by the ordinary drift again. 



Above the white clay, and filling up the undulation in it, is 

 a bed of yellow friable sand about three feet thick ; it is very 

 finely bedded, the planes being visible even in small hand 

 specimens. The rounded character of the grains and general 

 appearance of this sand at once show it to be derived from 

 the yellow sands of the Permian formation of this district. 

 To the east the sand and clay are entirely distinct, but 

 towards the west, before the white clay dies out, bands of 

 sand are found in it. Further on still the sand overlies the 

 clay, its western end resting on the rock before mentioned — 

 a hard, white, coarse-grained Coal Measure sandstone. The 

 ordinary drift covers the whole of the section from a few 

 inches in thickness at the eastern to ten or twelve feet at 

 the western end, where it occupies the whole exposure. 



The clue to the origin of these deposits is obtained on 

 drawing a section of the district where they occur, when it is 

 seen that the sands are found very close to the place where 

 the yellow sands of the Permian should outcrop. 







Fig. 4. Section across the district. 



I. 



Coal Measure sandstone. 



5. Drift (containing lacustrine 



2. 



Yellow Sands. 



deposits). 



3- 



Marl Slate. 



A. Outlier of Permian strata. 



4- 



Magnesian Limestone. 



X. Position of cuttings. 



Towards the close of the Glacial Period, a warmer state of 

 the climate than usual caused the ice to melt away from lower 

 levels, small streams being formed in all suitable positions, 

 carrying off the water so produced. One of these streams 

 flowing rapidly down from the Magnesian Limestone outcrop, 



