258 C. H. SMYTH, JR.—WEATHERING OF ALNOITE. 
on the one hand, and of Shaler,* Hilgard,f and Penrose,{ on the other. 
A decided impetus has recently been given to the study of weathering 
in general, both as to the processes involved and the results attained, by 
Dr G. P. Merrill’s admirable series of papers, published in this Bulletin,§ 
and by his book, “A Treatise on Rocks, Rock Weathering, and Soils.” || 
He has furnished numerous valuable data, together with the generaliza- 
tions to which they lead, and has done much to establish a rational 
method for the study of problems in weathering. 
In the following pages the writer presents the results of an investiga- 
tion, largely based upon Merrill’s methods, of an instance of weathering, 
which has especial interest in being well advanced, situated in a tem- 
-perate climate, and apparently quite narrowly limited as to time. 
LocaLiry 
The rock to be considered is exposed on both sides of the Hast Canada 
creek, which is the eastern boundary line of the town of Manheim, Herki- 
mer county. The locality is of peculiar geological interest on account 
of the dikes present and the fault so beautifully exhibited; and it is 
quite familiar, the latter feature having been figured in at least three 
publications.§] On the east bank of the creek three dikes are shown— 
one at the fault, another a few rods upstream, and the third two or three 
rods farther upstream. The latter dike is the largest of the three, having 
a width, with included horses of country rock, of about six feet. It was 
first exposed by blasting, done in connection with building operations 
some two years since, but now, unfortunately, is almost entirely covered. 
On the west bank only one dike is shown. It is impossible to trace 
this across the stream to connect it with either of the dikes there, and 
the exposures on both sides are so limited that the trend of the dikes 
can not serve as a positive euide, but there can be no reasonable doubt 
that the dike on the west bank is the continuation of the large dike. The 
decrease in width to about thirty inches is due in part to the absence 
of horses of the wall rock, and in part to a variation in the width of the 
fissure. 
APPEARANCE OF Rock IN THE FIELD 
The varying character of the rock in the field has been briefly stated 
* N.S. Shaler: The origin and nature of soils. Twelfth Annual Report U.S. Geol. Survey, p. 213. 
+E. W. Hilgard: The relation of soil to climate. Bull. 3, U.S. Weather Bureau. ; 
{R. A. F. Penrose, Jr.; The superficial alteration of ore deposits. Jour. of Geol., vol. ii, p. 288. 
2 Vol. vi, pp. 321-332; vii, pp. 349-362; viii, pp, 157-168. 
| The Maemillan Company, New York, 1897. 
q Geology of New York, pt. iii, p. 207. , 
Thirteenth Annual Report State Geologist of New York, i, plate facing p. 414. 
W. B. Scott’s Introduction to Geology, p. 247. 
