GEOLOGICAL SURVEY OF FORTIETH PARALLEL. 309 



Probably the final conclusion reached in the discussion of the origin 

 of granites, to which Mr. King has certainly contributed many new 

 and interesting facts, will be that each of the causes, heat and pressure, 

 should be credited with a share of the effects produced. 



Palaeozoic. One of the most interesting and surprising results of 

 Mr. King's exploration is the discovery of a section of stratified and 

 unmetamorphosed strata said to be conformable throughout, reaching 

 from the base of the Cambrian to the top of the Carboniferous, and 

 attaining a maximum thickness of 32,000 feet. No section of the Palse- 

 ozoic rocks of equal magnitude has yet been discovered elsewhere in 

 the world, and the announcement will doubtless be received with some 

 incredulity by geologists, but the accuracy with which the measure- 

 ments were taken by Mr. King and his assistants, and the vindication 

 of his classification afforded by the fossils, which were carefully re- 

 viewed by Mr. Meek, Professor Hall, and Mr. Whitfield, seem to leave 

 no room for doubt. This great group of rocks is said, as before stated, 

 to have been laid down in a basin bounded on the east by the ranges 

 of the Rocky Mountains in Colorado, and on the west by a broad 

 archsean area in Nevada. In the middle rose the lofty islands of the 

 Wahsatch, which toward the west presented an abrupt slope of 30,000 

 feet, aerainst which the Palaeozoic rocks abutted. From the inclosed 

 character of this sea most of the sediments formed in it are mechanical, 

 and represent the wash from the adjacent land, but in the middle of 

 the section occurs what Mr. King calls the Wahsatch limestone (Lower 

 Carboniferous and Upper Devonian), seven thousand feet in thickness. 

 Although no certain measure of time is afforded by the mechanical 

 sediments since the rapidity with which they were deposited may have 

 varied indefinitely with the activity of eroding agents this great lime- 

 stone mass, formed as it must have been through organic agencies, 

 represents a lapse of time which is almost beyond the reach of the 

 imagination ; and if, as Mr. King states, the Palaeozoic series is essen- 

 tially conformable throughout the area it occupies, we have here evi- . 

 dence of a stability in the physical conditions of this portion of the 

 earth's surface, which, so far as known, is without parallel. 



Mr. King gives two sections of the Palaeozoic series taken, one in 

 the Wahsatch Mountains and the other in Middle Nevada, which differ 

 only in minor details. The Wahsatch section is, however, the most 

 complete, as it shows the base of the Cambrian system, which is not 

 visible farther west ; it is as follows : 



1. Permian 615 feet - 



2. Upper Coal Measure limestone 2,000 



3. Weber quartzite, Carboniferous, and Devonian 6,000 



4. Wahsatch limestone, Carboniferous, and Devonian 7,000 



5. Ogden quartzite, Devonian 1,000 



6. TJte limestone, Silurian b 000 



7. Cambrian silecious schists 11,000 



8. Cambrian slates 800 



