Buckley — Ice Eaniparis. 149 



The limbs of these folds dipped in various directions, and at 

 different angles. The limbs of one of the folds dipped respec- 

 tively 38° west and 38*^ east; the limbs of another dipped 65° 

 west and 78° west, and a third had limbs which dipped 70° east 

 and 60° east. In this small area all classes of folds were repre- 

 sented, normal, overthriist, and imderthrust. Each of the folds 

 was sharply fissured nearly the entire length of its axis. Cross- 

 fractures were of common occurrence, and in a number of in- 

 stances they were accompanied by conspicuous faulting, as 

 shoAvn in Plate XII. In this instance the fold has parted in 

 the middle, one-half having moved horizontally past the other. 

 Faulting had also occurred along the crest parallel to the axis 

 but the movement between the limbs was not very great. In 

 many instances the fractures were open and the walls had sep- 

 arated for a space of one or more inches. Many of the arches 

 were hollow, although some appeared to have very little vacant 

 space between the limbs. Some of the folds died out gradually 

 at the ends, but in many cases their termination was quite 

 abrupt. 



It was evident that the anticlines had risen much more than 

 the synclines had been depressed. In fact the synclines had, in 

 only a few places, the appearance of having been depressed be- 

 low their former level. 



It was observed at this locality, and elsewhere, that the char- 

 acter of the folds and the rigidity of the shore line were closely 

 related to each other. Wherever the folds were near a rigid 

 shore line they were almost invariably overthrust. Where the 

 rigid bank was absent, or distant, the folds were generally nor- 

 mal or underthrust. These relations existing between the bank 

 and the folds were observed in a sufficient number of places 

 along the shore of both lakes, to show the interdependence of 

 the two. 



CAUSE OF ICE RAMPARTS. 



The cause of ice ramparts as expounded by G. K. Gilbert in 

 his classical monograph on Lake Bonneville, is well known to all 

 students of geology. It is as follows : 



^'The ice on the surface of a lake expands while forming, so 

 as to crowd its edge against the shore. A further lowering of 

 temperature produces contraction, and this ordinarily results in 



