Vol. 6] Eeid: The Cfeomorphogeny of the Sierra Nevada. 125 



The Franktown Area. — The Franktown topographic area ad- 

 joins the complex Carson area on the north. Although it is al- 

 most entirely composed of granitic rocks, it furnishes some def- 

 inite proof of the relative ages of faults, or lines of faults. It 

 contains the most striking physiographic feature of the whole 

 region — Little Valley, a large, well-formed intra montaine longi- 

 tudinal valley. The Franktown and Carson topographic areas 

 are separated by a fault-line through Incline and the south end 

 of Washoe Lake. South of this line there are three longitudinal 

 ridge lines, as already noted. North, in the Franktown area, 

 there are but two ridge lines, a high western one, that forms the 

 true crest, and a low eastern one, just above Washoe Valley. A 

 few buttress-like crust blocks also are present, as are evident 

 from the topographic map, east of Incline. Besides these larger 

 forms there are many smaller ones, some of which, in the south- 

 ern part of Little Valley, have received notice. In the north 

 part of Little Valley there are a number of small blocks which are 

 so peculiar that especial notice is deserved. 



Climbing westward from Washoe Valley near Franktown, 

 the low east ridge is ascended, over the granite fault-scarp rising 

 out of the valley floor. From this ridge summit one looks east 

 straight clown to the valley 1,400 feet below, and west, first down 

 gently to the level floor of Little Valley, then beyond to the mas- 

 sive and imposing granite wall which rises unbroken for over 

 2,000 feet to the range summit. From the range crest the slopes 

 descend steeply to the west, except in the northern part. Little 

 Valley itself thus lies between two ridge crests, and strikes about 

 north and south. It is clearly a structural feature, following the 

 longitudinal fault of the high scarp to the west. The features of 

 this valley furnish a clue to the explanation of much of the fault- 

 ing of the region, and will therefore be described in detail. Fol- 

 lowing this description, a critical examination will be made of 

 the several features, and conclusions drawn regarding their 

 significance. A portion of Little Valley lies within the Carson 

 topographic area, but the valley will here be treated as a physio- 

 graphic unit. 



An east-west cross-section through the central part of Little 

 Valley shows it to occupy the low area between two crust blocks, 



