Alluvium, Craig, &c., 600 feet . 



Chalk, 1000 



Green Sand, 500 



Wealden, 1000 



Oolite and Clays, 1500 . . . . 



Lias, 500 



Upper New Red Sandstone and 

 Magnesian Limestone, 1400 . . 



Coal Measures, 3000 



Millstone Grit, 1000 



Carboniferous Limestone, 2000 . 



Old Red Sandstone, 3000 



TERTIARY 

 STRATA. 



UPPER & 



MIDDLE 



SECONDARY 



STRATA. 



Ludlow Shales, 2000 . . 

 Wenlock Limestone, 1500 

 Caradoc Limestone, 3000 

 Llandilo Flags, 1000 . . 



LOWER 

 SECONDARY 

 [ STRATA. 



Slates 



Schists 



Gneiss 



Granite 



PRIMARY 

 STRATA. 



FIG. 1. DIAGRAM SHOWING THE POSITIONS AND RELATIVE THICKNESSES 

 OF THE STKATA. 



