CONTEMPORANEOUS DEFORMATION 



787 



kind of distortion, which is beheved to have been contemporaneous 

 with the accumulation of the strata/ 



The Squantum slates described. — -On the eastern coast of Squan- 

 tum Head, in Boston Harbor, Massachusetts, is a series of slates 



■:y<. 



""■•^owSl^ 



^'^<.' 

 i-^")*^ 



Fig. I. — The Squantum banded slates. Near the middle of the picture is a zone 

 in which the strata have been closely folded. Above this zone may be seen an isolated 

 pebble, about three inches in diameter, which is thought to have been dropped by 

 floating ice. 



overlying the Squantum tillite.^ The formation is of late Car- 

 boniferous or of Permian age. The slates are very fine-grained 



' The same type of distortion was described by James Geikie in clay beds overlying 

 till at Portobello, Scotland; see his Great Ice Age (3d ed., New York, 1895), pp. 271-74. 



= R. W. Sayles, "The Squantum TilHte," Btdl. Mus. Comp. ZooL, LVI, No. 2 

 (1914), 141-75- 



