OGDBN EEGION. " 401 



Athyris planosulcata, 



jEuompJialus (StraparoUus) Utahensis, 



Slreptorliynclms eqiiivalvis, 



Streptorhynchus inequalis, 



Proetus peroccidens, 



of which the two latter have a Devonian aspect. 



From the upper beds of the Wahsatch hmestone, near the head of the 

 canon, were obtained portions of the interior of a Zaphrentis, showing evi- 

 dence of a small curved species, but too poor for identification. Along- the 

 bottom of Ogden Caiion occurs an interesting formation of Quaternary 

 gravel, which in places forms the bed of the stream, but is generally cut 

 through to a considerable depth, sometimes as much as 150 feet. It is evi- 

 dently a relic of the old Lake Bonneville, which once extended up into the 

 canon, under whose waters it was deposited. The coarser beds are made up 

 of large quartzite boulders and pebbles held together by fine ferruginous 

 gravel, forming a pudding-stone of considerable hardness, while the finer 

 beds are composed of comminuted siliceous and feldspathic rocks, a variety 

 of till derived from the material brought down by the stream. In the Ogden 

 Quartzite, on the north side of the canon, occurs a warm sulphur spring, 

 which has a considerable flow of tepid water, and is highly charged with 

 sulphurous vapors, the surface of the ground around being coated with a 

 deposition of yellow sulphur. At the entrance of the canon are two small 

 thermal springs, which are slightly charged with salts of iron. They have 

 a temperature of about 150°, and around one of them is a considerable 

 deposit of calcareous tufa, which would indicate that the water came up 

 tlu'ough the limesto^ie-beds which have been faulted down from the west 

 face of the range. The old lake-terraces are particularly distinct in the 

 neighborhood of Ogden, consisting mostly of uncompacted gravel and some 

 beds of loose sand. In places, however, the calcareous cement has more or 

 less consolidated the gravel into a -loose conglomerate. No less than thir- 

 teen of these terrace-lines can be traced back of Ogden. 



To the north of Ogden Canon, the extreme foot-hills of the range are 

 occupied by the Archaean body already noticed, above which the Cambrian 

 quartzites and Silurian limestones can be distinctly traced by the different color 

 20 D G 



