METAM ORPHIC SERIES OF SHASTA COUNTY. 589 



paper deals chiefly with that part of Shasta county which bor- 

 ders upon the McCloud and the Pitt rivers, where the writer 

 was during the summer of 1893. 



STRUCTURE. 



Folds. The region is preeminently a folded one, although 

 the folds are obscure 'except along the water courses, and the 

 anticlines are often overthrown. This, together with the scarcity 

 of fossils in the shales, and the monotonous character of the 

 rocks, renders the structure hard to unravel. These folds are 

 seen chiefly in the siliceous shales of the Pitt formation, the 

 Carboniferous limestone of the McCloud being chiefly an east- 

 dipping monocline, and the Triassic limestone of Squaw creek 

 appearing as a series of short monoclines, usually with an east 

 dip, and with some imperfect folds. The siliceous shales are 

 usually on edge, with a strike of 25 west of north. The folds 

 are nearly all short, and since the streams run with the strike, a 

 peculiar effect is seen — the streams are constantly cutting across 

 the strike in running from one synclinal trough into another. 

 The ends of the anticlines are soon worn down deeply, until one 

 loses the effect of anticlinal "noses," and is inclined to think 

 that the stream has cut directly through the axis by means of a 

 fault. 



East of the fork of Squaw creek, near Kelley's ranch in the 

 space of one mile there were seen in the siliceous shales three 

 small anticlines. In these cases the arches of the anticlines were 

 actually seen, but in most cases the folds are so sharply jammed 

 together, the erosion so great, and the rocks so similar through- 

 out the section that it was impossible to see the detailed struc- 

 ture. 



Faults. While faults have not had such a great influence on 

 the general topography as folds, still they have influenced to a 

 greater degree the local details. In the siliceous shales of the 

 Pitt formation faults can not be distinguished, but only surmised. 

 In the limestones, however, they can easily be found. 



East of the McCloud river the Carboniferous limestone for a 



