HURRICANE FAULT IN SOUTHWESTERN UTAH 



59 



been like those of its tributaries — a broad open depression 

 where the river flowed on an extensive flood-plain close to base- 

 level. Near the end of this cycle of erosion there was exten- 

 sive aggradation, forming the heavy gravel deposits of Kanarra, 

 the Virgin river, and the Grand Wash. Then came an abundant 

 outpouring of basalt from many craters, especially in the region 



Fig. 7- — View south across the valley of the Virgin river at Rockville. The 

 sharp cliffs of Red Kanab sandstone in the background rise 3,000 feet above the 

 river. Below them are soft lower Kanab shales, the rapid weathering of which has 

 undermined the Upper Kanab, causing the great landslides that are seen lying on the 

 Shinarump platform which extends across the middle of the picture. Below the 

 Shinarump the soft Verkin shales are minutely dissected into a bad-land topography, 

 whose roughness and aridity contrast strongly with the irrigated fields of the Mormon 

 village of Rockville on the flood-plain in the foreground. 



that was nearest baselevel ; and thus a new and very durable 

 element was introduced into the topography. 



THE HURRICANE FAULT THE LATER FAULTING. 



The newer displacement, like the older one, changed at 

 ToquerviUe from a fault into a flexure. South of Toquerville, 



