176 WILLIAM J. MILLER 
cylindrical form which seems to be implied in the term boss (or stock)... .. 
The space which they (bosses or stocks) occupy can scarcely have been pro- 
vided by the thrusting aside of the contiguous rocks, assisted by some con- 
traction of the latter in metamorphism. They appear, as Barrois says of the 
granite of Rostrenan in Brittany, to have penetrated the solid rocks by cutting 
a way through them like a punch, not by thrusting them aside like a wedge. 
In such cases we may suppose that “‘stoping”’ has played an important part. 
Daly, speaking of granite stocks and batholiths, says:" 
Most, if not all, of these bodies in their accessible portions have replaced 
nearly equivalent volumes of their respective country rocks. They are 
generally cross-cutting bodies. ... . Where erosion has been profound, the 
ground plan section of the typical stock or batholith is seen to be elliptical. 
Both in ground plan and in vertical sections the contact surface is 
relatively smooth. Apophysal offshoots do interrupt the wall-rock, but the 
main contact lines as mapped on ordinary geological maps are characteris- 
tically flowing lines. Large scale, angular projections of country rock into 
well uncovered batholith are comparatively rare. Such smoothness of main 
contact surfaces is that which is to be expected on the stoping hypothesis. 
These statements by Harker and Daly are precisely descrip- 
tive of the mode of occurrence of the typical basic stocks of the 
North Creek region. Stock No. 1 (see map) already described 
is a fine example. This rock was certainly not intruded by dis- 
placing or simply pushing aside the country rock, but rather it 
was a process of replacement. Thus the mode of occurrence of 
the North Creek stocks furnishes strong evidence in favor of mag- 
matic stoping as an important factor in the intrusive process. 
SIGNIFICANCE OF THE INCLUSIONS 
A good proportion of the stocks contain inclusions of country 
rock. Among many examples are the following: 1% miles north- 
northeast of The Glen; 1 mile south-southeast of The Glen; 14 
miles south of South Horicon; and 1% miles northeast of Potters- 
ville. These inclusions, which are seldom more than a few feet 
long, are usually angular and irregularly arranged in the matrix. 
It is quite the rule that the dark colored minerals of the gabbro 
are arranged with long axes parallel to the long axes of the inclu- 
sions, this probably having been due to a sort of flow structure 
t Amer. Jour. Sci., XXVI (1908), 20. 
