PRELIMINAKV^ CONSIDERATIONS. 



impiy precipitation of carbonate of lime and magnesia in the 

 sea-bottom. The marls must have been formed largely by the 

 driftage of sand and clay, while some of the limestone was 



12 



'4 



'5 

 i6 



17 



^78' V 



276' 0" 



=43 o 



30' ti" 

 32' i" 



■< '■"., 



6 10" 



34' 10" 



80 7 ' 



13' 5' 



7 o' 

 13' 6" 



135' 6" 



6'o" 



132' o" 



Total— 1,517 ft 



Fig. 3.— Section obtained by bonng with the diamond drill, near Goderlch, Ontario, 

 Canada, in the Salina series of the Upper Silurian. From a memoir by Dr. Hunt 

 in the Report of the Geological Survey of Canada for 1876-7. 



No. 1, Clay, gravel, and boulders— Post-pliocene. Nos. 2, 4, 7. 9, 13, Dolomite or 

 magnesian limestone, with layers of marl, limestone, and gypsum. No. 3, Lime- 

 stone with conxh^—Favosites, etc. Nos. 5, 11, 15, 17. Marls with layers of 

 Dolomite and anhydrous gypsum. Nos. 6, 8, 10, 12, 14, 16, Rock salt. 



