342 bulletin: museum of comparative zoology. 



by Dr. Friedrich Schmidt. The other view appears to have been 

 first broached by Hisinger. According to him, the strata of Gotland 

 are essentially horizontal with only a slight dip to the east, so that 

 the same beds are found over many parts of the island. This view 

 received strong support from Helmerson, F. Roemer, Angelin, Bather, 

 StoUey, Wiman, Dames, and Lindstrom. 



Among the latest published studies of the stratigraphy of Gotland 

 are those from the pens of Drs. Henry Munthe and Herman Hedstrom, 

 the former having studied the southern and the latter the northern 

 half of the island. With some modification, Munthe appears to be in 

 general agreement with the second view, while Hedstrom appears to 

 adopt the views of Murchison and Schmidt with, however, considerable 

 changes. 



In general, the strata of Gotland have been said to fall into two 

 lithic divisions; a lower, consisting of calcareous shales, thin lime- 

 stones, oolite, and sandstones, and an upper, consisting of coralline 

 and crinoidal limestones with subordinate shales. This grouping has 

 been previously noted by Holm, Munthe, and others. It has generally 

 been considered that the boundary between the two divisions is fairly 

 sharp, but it is by no means certain that such is the case, since much 

 which has been considered evidence of sharp division is capable of 

 a different interpretation. 



The detailed work of Munthe over the southern part of Gotland 

 has given the classification which follows. The divisions are named 

 from the summit downward. 



la Ascoceras limestone. 



lb Youngest crystalline limestone. 



2 Ilionia or Spongiostroma limestone. 



3 Upper Sphaerocodium bed and oolite. 



4 Sandstone with clay. 



5 Lower Sphaerocodium bed. 



6 Dayia flags. 



7 Marl shale with lenses and bands of limestone.^ 



For northern Gotland Hedstrdm lias offered the following sub- 

 divisions, named in order from the highest to the lowest. 

 VII. Nonstratified reef limestones or stratified crinoidal and coralline 



limestones. 

 VI. Leperditia shales. 

 V. Oolitic limestones. 



1 Munthe. Guide book 11th. internat. geol. congr., 1910, no. 19, p. 49-50. 



