270 PETROLOGICAL ABSTRACTS AND REVIEWS 
of the slate have been submerged in the granite, and partially absorbed, 
giving rise to schlieren. ‘Transferring this observation to large areas of 
schists, a part of them have been designated as “‘gneisses of injection”’ 
and still another as mixed rocks. Injection of materials is also connected 
with direct contact metamorphism, often resulting in recrystallization 
under pressure—piezo-crystallization. Weinschenk designates those 
schists whose development was conditioned by piezo-contact metamor- 
phism as ‘“‘alpine facies,” and as normal facies those schists which have 
been developed through impregnation, injection, and resorption without 
the agency of pressure. 
The conception that the action of mineralizers on sediments con- 
tributes to the origin of schists has been extended by Termier (1901, 
1903) to explain the origin of lenses of peridotite, gabbro, or amphibo- 
lite concordantly imbedded in sediments. He regards them as materials 
which have risen from the deeps along bedding planes, somewhat like 
a large oil globule, and have locally converted the sediments into roches 
vertes. 
Lepsius and Giirich have attached themselves to the French views 
more fully than other Germans. Lepsius with Barrois emphasizes the 
absorption of contacts by rising granite magmas; while Giirich has 
emphasized the action of mineralizers rising from magmas. Lepsius 
(1903) has maintained that the injection of a granite laccolite concordant 
with the parallel structures of the intruded rocks results in the intrusive 
forming granite gneiss, while with discordant injection it forms a massive 
granite. In both cases large quantities of the intruded rocks are 
absorbed, giving rise to variations in the composition of the intrusive. 
Giirich (1904), on the other hand, maintains that the material alteration 
of sediments and their conversion into gneisses is not due to a granite 
magma rising from the deeps, but is accomplished by the melting of 
compressed solid granites enveloped by sediments, on sudden release of 
pressure which results in absorption of the inclosing schists and alteration 
to gneiss. 
Haug conceives that in geosynclinals, heat, pressure, and ascending 
mineralizers are sufficient to melt or partially convert sediments into 
granite magmas which consolidate into magmas on cooling. LeClere 
(1906) and P. Termier (1907), having similar views, hold that from the 
upper portions of the masses converted into granite magmas very little 
injection and impregnation of the surrounding rock results. The action 
of mineralizers in the upper portions has been just sufficient to convert 
the rocks into a granite magma. 
E. STEIDTMANN 
