134 QnCKSlIA'ER DEPOSITS OF THE PACIFIC SLOPE. 



crumple the overlying strata by horizontal translation over the granitic 

 surface while the gi'anite remained undisturbed, and it therefore inevitably 

 follows that the granit-e must have been fissured and crushed or deformed, 

 01', more probably, crushed in the higher portions and plastically molded 

 in the deeper regions. The granite, like the sedimentary rocks, must have 

 been heated by the conversion of sensible motion into molecular motion. 



Nearly all rocks are permeable by water, and in every region there is 

 a system of percolating, subterranean currents. There must have been 

 such systems in the sedimentary and massive rocks of California before 

 the great upheaval, and this system must have been as thoroughly dis- 

 turbed at the uplift as were the rocks themselves. Old vents were closed, 

 porous beds compressed, and the fractures caused by the convulsion cer- 

 tainly afforded new paths of weak resistance. The waters were warmed 

 by the heated rocks, and consequently became more powerful solvents, 

 and cannot but have attacked many of the minerals with which they were 

 in contact. 



So far all the circumstances appear simple and certain, and it may be 

 added that, since the uplift as a whole bears the character of a violent com- 

 pression, the interstitial sj^ace was probably greatly diminished and the 

 heated mineralized waters were driven toward the surface When one at- 

 tempts to pursue the subject further and to reason upon the special char- 

 acter of the mineral water.s, or the particular temperature, or the ensuing 

 reactions, observation appears to be the only guide. A priori it is clear 

 only that very considerable modifications in the character of the sedi- 

 mentary rocks must be expected and that as the action diminished a series 

 of transformations might occur. So far as can be known, there is nothing 

 unreasonable in the supposition either that the solutions may have been 

 basic at some points and acid at others or that at the same points they 

 may have been basic at some stages of metamorphism and acid at others. 



Chemical indications. — Tlic pscudodiabasc aud pseudodiorite are much more 

 basic than the sandstones, as is also the serpentine, while the phthanites 

 are more acid than the shales from which they are derived. Serpentin- 

 ization and silicification have often gone on in the same rock mass, and 

 the evidence from many widely separated localities appears to indicate that 



