28 The American Geologist. Jaly, 1894 
bly of Lower Karnic age. The limestones are considered by 
him as the equivalent of those on Cedar creek, south of Pitt 
river. In relation to the Taylorsville Trias, he considers the 
limestone equivalent of the Hosselkus limestone, and the un- 
derlying Ammonite slates the equivalent of the Halobia slates. 
The conclusion based on a study of the field was that the 
Squaw creek limestone and associated fossiliferous strata oc- 
cupy an intermediate position between the Jura of Big canon 
and the Carboniferous of the McCloud. The argillaceous slate 
below the limestone is followed in the direction of Squaw 
creek by silicious slates, having a nearly vertical dip. In the 
latter, fully 2,000 feet below the limestone, several poorly 
preserved specimens of brachiopods were found. 
The silicious slates continue southward and are probabl}" 
the equivalent of those at Silverthorne's ferry, where there is 
an exposed thickness of nearly 2,000 feet. According to 
the paleontological evidence obtained here by J. P. Smith, 
he would place these slates in the Middle and possibly the 
Lower Trias, of which there are no equivalents at Taylors- 
ville. It is intended to apply the term Pitt shales to ' these 
rocks, which, together with some Upper Carboniferous strata 
(McCloud shales), twenty miles above the Fisheries, shall be 
embraced under the designation Pitt formation. 
The Carboniferous of the McCloud River. — The Gray or 
Marble mountains of the McCloud river, as a high and rugged 
range, border that stream for many miles on the east. In the 
vicinity of the United States fisheries the scenery is very 
picturesque. The limestone is much disturbed, in places be- 
ing nearly vertical, in others dipping to the east at an angle 
of thirty degrees or less. Whitney estimated the thickness 
at the fisheries as 1,000 feet, but it seemed to the writer 
much greater, probably twice that amount. Dr. Trask collec- 
ted the most of his fossils from near Basses ranch south of 
Pitt river, the limestone being the southern continuation of 
that on the McCloud. 
The lowest horizon recognized at the fisheries is a black 
silicious shale, probably 500 feet thick (Baird shales), the 
fauna of which Mr. Smith considers analogous to the Waverly, 
but that the strati graphical position is higher. The fauna 
is chiefly molluscan. This fauna seems to appear at a mini- 
