128 KANSAS ACADEMY OF SCIENCE. 
land. Bone and Necker, nearly a quarter of a century later, transported the the- 
ory from this Plutonic region to Europe, where it reached greater development. 
The Alpine region, on account of the great forces at work and the gradations in 
effects, from the simple to the complex, soon became a classic region for the study 
of rock alterations. In 1826 Beaumont recognized that in this region the phe- 
nomena were 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 region was greatly increased. 
In the process of adjustment of the minerals or rocks to changes in their envi- 
ronment, new elements are often added and old ones removed. If the changes 
take place at the surface of the earth, under ordinary atmospheric or aqueous 
influences, they are included under the term weathering, and the result is usu- 
ally disintegration. True metamorphism is connected with igneous and dynamic 
agencies; and while the word was first introduced by Lyell, in 1832, it was not 
clearly defined until 1846, when Durocher described metamorphism as the sum 
total of all modifications in texture or structure to which rocks in nature are sub- 
jected. Daubrée limited the definition to those modifications whose causes were 
fire and water, and Beaumont added the agency of mineralizers. The word meta- 
morphism is now cosmopolitan, though given different limitations by different au- 
thorities. 
American geologists from an early day have been prominent in this field of 
study. The pioneers composing the American metamorphic school — Hitchcock, 
Mather, Dana, Logan, Rogers brothers—were active students of those altered 
records, and they made many valuable observations. They all regarded the 
process of metamorphism as confined to the sedimentary rocks, a view which 
long retarded progress in the work. When foliated or parallel structures were 
observed in metamorphic rocks, they were regarded as the old sedimentary lines 
which survived the alteration. A voluminous literature descriptive of this lim- 
ited field of altered sediments soon filled the shelves of science. 
Down to the year 1875 the province of metamorphic action was thus confined 
to the sedimentary rocks. About this time appeared the epoch-making works 
of Heim, in the Alps, and of Lossen, in the Hartz, whereby it was shown that 
igneous rocks could be changed by metamorphic action. 
On account of the interesting and inviting problems connected with this 
study, it has attracted the attention of many of the younger workers; and the 
result has been a very great advance in our knowledge of these broken and 
crumpled rocks, though the vast field yet remains practically unexplored. 
Metamorphism may refer to any changes in rocks, but it is restricted now to’ 
include the changes whose conditions lie intermediate between fusion and ordi- 
nary atmospheric action. The limits are not sharply defined, so metamorphism 
grades below into igneous action, and above into atmospheric action or weather- 
ing. Metamorphic rocks may be further metamorphosed, so that all rocks, 
sedimentary, igneous, and metamorphic, are subject to metamorphism. The 
agencies at work in this great process are both physical and chemical; and they 
are classified according to the preponderating influence. If the temperature and 
pressure are low the action is due mainly to water, producing hydro-metamor- 
phism, resembling very closely weathering. If temperature is high and pressure 
is low, and mineralizers — gases whose presence facilitates fusibility —are present, 
the action is described as sublimation metamorphism; or, if water alone be 
present, the action is described as thermo-metamorphism. Static metamor- 
phism includes those changes where pressure is mainly active and where motion 
is absent. If motion is present, the changes come under the division of dynamic 
