G. W. Robinson and C. F. Hill 



261 



the geological map. Millstone Grit and Gwespyr Sandstone are found 

 to a small extent in Flintshire to the east of the Carboniferous Lime- 

 stone. Coal Measures are found over a wide area of Flintshire and 

 Denbighshire, but are generally obscured by drift. The Permian and 

 Triassic formations are also generally drift covered. Isolated outcrops 

 of Trias occur near Ruthin and Denbigh^ 



North Wales. Eainfall. 



2.5 to 30 inches 

 30 to 35 inches 



Jlean Annual Eainfall 



35 to 40 inches 



'fy'^''y"?% 40 to 45 inches 

 Over 100 inches 



E 



45 to 50 inches 



50 to 100 inches 



The chief feature of our region is, however, its glacial geology. North 

 Wales has been subjected to two glaciations, namely the Northern 

 glaciation running roughly N.E. to S.W. and the Welsh glaciation 

 radiating from the mountain areas. The deposits from the two glacia- 

 tions are quite distinct. While the Welsh glacial drift consists mainly 

 of local material scraped down from the uplands, the Northern drift 



1 We have not examined any sedentary soils from the Trias. For a description of 

 Triassic soils, see A Survey of the Soils and AgricuHure of Shropshire, by G. W. Robinson. 

 Shrewsbury, UI13. 



