16 The American Geologist. Jannao, i897 
past decade the students of nature have discovered the exist- 
ence of natural palimpsesls and they are now endeavoring to 
read the imperfectly erased records of the past, and thus add 
new chapters to the liistory of the earth. To the process of 
erasure and rewriting these investigators have given the name 
metamorjihism, and the natural palimpsests are called meta- 
morphic rocks. 
The studies of the biologists have shown that throughout 
organic nature there is a most delicate adjustment to environ- 
ment. The researches of petrographers have shown that in 
the inorganic world minerals are so delicately adjusted to 
surrounding conditions that changes in the latter are recorded 
by variations in the minerals. The recognition of this fact 
in recent years is the foundation of the new knowledge con- 
cerning the Archiean period. 
According to the Wernerian theory of the last century, 
crystalline rocks were deposited as chemical precipitates from 
a primeval heated ocean before life existed ; they were pro- 
duced at their origin as they exist to-day. Near the close of 
the century, Hutton found granite dykes penetrating other 
rocks, thus proving an igneous origin. He then advanced 
farther and formed the interminable cycle, stating that rocks 
were decomposed by atmospheric action, the detritus accumu- 
lated at bottom of the sea, where under the pressure and heat 
it was rendered crystalline, and later elevated to pass through 
the same series of changes without trace of beginning or pros- 
pect of end. The theory of the transformation of rocks under 
heat and pressure originated at this time in this rudimentary 
form in Scotland. Bone and Necker, nearly a quarter of a 
century later, transported the theory from this plutonic re- 
gion to Europe where it reached greater development. The 
Alpine region, on account of the great forces at work and the 
gradations in effects, from simple to complex, soon became 
the classic region for the study of rock alterations. In 1826 
Beaumont recognized that in this region the phenomena v.ere 
not confined to the oldest rocks. He observed that Jurassic 
fossil sediments had been changed to crystalline rocks. The 
old Alps now^ became the new Alps and the interest in the re- 
gion was greatly^ increased. 
