PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 



237 



continuing to flow toward the lake valley the film was wrinkled by being 

 obstructed by its own stiffness as cream is wrinkled transversely on the edge of 

 a pan as the milk runs out below. * * * The crumpled layers are about 

 an inch thick, but sometimes two or three are infolded upon each other, making a 

 crumpled layer of three or four inches. They are much finer and denser in grain 

 and structure than the beds on which they lie, and are of a redder color. The convex 

 sides of the wrinkles are upward. * * Sometimes embraced in these wrinkled 

 layers are lenticular areas or patches half an inch to an inch and a half thick of 

 red grit, resembling the red sandrock with which these traps are associated, 

 and within the amphitheatre, near the water on the north side, is an irregular 

 triangular patch of ferruginous, thin bedded shale (No. 167), lying under a layer 

 of dark trap and over the beds that show these wrinkled surfaces. Five layers 

 of alternating trap and amygdaloid are visible between the lake and the first fall, 

 somewhat less than one-fourth of a mile up the river. 



Lake 2ine 



FIG. 16. SANDY, RED SHALE, NO. 167, BETWEEN LAVA SHEETS AT THE MOUTH OF TEMPERANCE RIVER. 



FIG. 17. ROPY WRINKLES ON THE LAVA FLOW OF ROCK NO. 170. 



The above figures represent the manner of occurrence of the shaly and pebbly 

 rock No. 167, and the wrinkles of the rock No. 170. 



