DESICCATION OF SALINE MUDS 



487 



In the other type the mud-cracks are much wider and extend downward 

 one or more inches. The latter are found over the larger part of the area 

 and characterize the clay with a copiparatively moderate amount of 

 salinity. The former are found near the salt-water brooks which cross 

 the playa where the clay is highly saline. 



Figure 12. — Mud-crack in Pamelia Limestone, Kingston, Ontario 

 Photograph by Dr. Kirtley F. Mather 



It would appear from these observations that the Pamelia limestone 

 mud-crack, with its slightly incised lines, represents highly saline muds, 

 while the type illustrated by the Mount Wissick^^ limestone mud-cracks 

 extending several inches into the rocks were formed in calcareous mud of 

 slight or moderate salinity. 



15 E. M. Kindle : Canada Geol. Surv., Mus. Bull. No. 14, 1914, pp. 35-39, pis. ii-iii. 



XXXVII— Bull. Geol. Soc. Am., Vol. 29. 1917 



