398 
TURNER. 
In 1872, in his paper on the “ Formation of the Great 
Features of the Earth’s Surface ” (VIII, page 355), Professor 
Le Conte says: 
“ I think, therefore, I am justified in asserting that the 
phenomena of plication and slaty cleavage demonstrate a 
crushing together horizontally and an upswelling of the 
whole mass of sediments, and that slaty cleavage demon¬ 
strates in addition that the upswelling produced by this 
cause alone is sufficient to account for the elevation of the 
greatest mountain chains.” 
On page 463 of the same article he further says: 
“ Mountain chains are formed by the mashing together 
and the upswelling of sea bottoms where immense thicknesses 
of sediments have accumulated, and, as the greatest accumu¬ 
lations usually take place off the shores of continents, mount¬ 
ains are usually formed by the uppressing of marginal 
sea bottoms. We will make this plainer by some illustra¬ 
tions taken from the history of mountain chains in North 
America. 
“ During the whole Triassic and Jurassic periods the region 
now occupied by the Sierras was a marginal sea bottom, 
receiving abundant sediment from a continental mass to the 
east. At the end of the Jurassic, this line of enormously 
thick, off-shore deposits yielded to the horizontal thrust and 
and the sediments were crushed together and swelled up¬ 
ward into the Sierra range. All the ridges, peaks, and 
canons—all that constitutes the grand scenery of these 
mountains—has been the restilt of an almost inconceivable 
subsequent erosion.” 
In 1874 Professor Le Conte writes (IX, page 180): 
“ The Sierra range was first formed at the end of the Jurassic 
by mashing together and up-swelling only, while its subse¬ 
quent slight increase at the end of the Tertiary was attended 
with great fissure-eruptions.” 
