22 T. STERRY HUNT ON THE GENETIC 
from it the elements of orthoclase and quartz. With the disappearance of the latter would 
come the elements of the more basic feldspars, such as andesite and labradorite, as well as 
protoxyd-silicates, which together predominate in the norites and the diorites, charac- 
teristic crenitic rocks of the later crystalline series, such as the Norian and Huronian, which 
succeed the granites and the granitoid gneisses of the earlier periods. 
The crenitic hypothesis, as we have elsewhere seen, involyes the conception that all 
trachytic and granitic rocks are primarily of crenitic origin, and that penetrating granitic 
masses, when not, as is the case with most granitic veins, directly crenitic or endogenous 
masses, are displaced portions of older crenitic deposits. The first-formed granitic layer 
itself, it is held, may become softened under the combined influences of water and internal 
heat, and being then displaced, may appear in an eruptive form. 
§ 36. The question here arises as to the respective parts which crenitic action, on the 
one hand, and crystallization and eliquation, on the other, may play in the genesis of 
various types of crystalline rocks. It is apparent, from the illustrations which we have 
given, that by the latter process aggregates could, in paleeozoic times, be formed in which 
chrysolite makes more than one half the weight of the mass, and others in which either 
pyroxene or labradorite may largely predominate. The texture and the general facies of 
these different mineral aggregates, not less than their geognostic relations, however, suffice 
to distinguish them from crenitic deposits of somewhat similar composition. It was from 
a failure to recognize these differences that the original Wernerians denied or minimized 
the significance of igneous rocks, on the one hand, and that the later plutonists of both 
schools on the other hand, have argued the igneous origin of rocks of manifestly crenitic 
origin. The Wernerians, from the stratiform structure of gneiss, which they ascribed to 
its aqueous origin, argued for a similar origin for the granite into which it appears to gra- 
duate, while the plutonists from an analogous structure in undoubtedly igneous rocks 
conclude the igneous origin of gneiss. We have already noticed this laminated or stra- 
“tiform character in plutonic rocks, the true significance of which, as evidences of igneous 
flow, should not be lost sight of. 
§ 37. It must be kept in mind that the crenetic process, unlike eliquation, modifies 
the primary mass not only by abstraction, but by addition, since the surface-water which, 
by the hypothesis, is the dissolving agent, will bring with it in solution, in varying pro- 
portions, salts of calcium and magnesium, of potassium and of sodium, the action of all 
which upon the heated plutonic mass will effect certain interchanges, resulting in the 
fixation of bases like magnesia, whose silicated compounds are comparatively insoluble 
in the circulating waters, and perhaps in a substitution of soda for lime. It is not impro- 
bable that potassic solutions from some local source ! could thus be introduced, and give 
rise by their action upon a doleritic mass, either integral or partially differentiated by eli- 
quation, to a material so rich in potash as to furnish the elements of leucite, which has 
the oxygen-ratios of an andesite. 

1 While in ordinary spring-waters the proportion of potassium to sodium salts is small, seldom exceeding two 
or three hundredths of these bases, calculated as chlorids, I have shown that in an alkaline spring-water from 
paleeozoic shales at St. Ours, Quebec, containing in a litre about 0.3 gramme of alkalies, chiefly as carbonates and 
chlorids, the potassium thus calculated equalled 25 per cent. In the case of the water of the St. Lawrence River it 
equals 16 per cent, and of the Ottawa River 32 per cent. See for a discussion of the question of potassium in natural 
waters, the writer’s Chem. and Geol. Essays, pp. 125-137. 
