126 
The American Geologist . 
February, 1896 
geologists, it was held that one of these structures develops 
normal to the pressure in a deep-seated zone of rock-flow, and 
that this ought properly to be called “cleavage.” Following 
Becker, it was held that there have often developed two inter¬ 
secting structure or shearing planes in the zone of fracture. 
For this structure the term “fissility” was proposed. 
Dr. Becker in discussing Professor Van Hise’s paper ex¬ 
pressed himself as certain that true cleavages as well as rup¬ 
tures are produced at large angles (not necessarily 45°) to 
the line of force. He regards the existence of such cleavages 
as well established, both by experiment and by theory. In his 
opinion no adequate theoretical or experimental basis exists 
for asserting that cleavage is normal to force, and field obser¬ 
vations on slates have the exact direction of force to inference. 
W. F. Morsell. 
Wisconsin Academy of Sciences. 
The Wisconsin Academy of Sciences, Arts and Letters held 
its annual meeting at Madison December 26th to 28th. The 
plan for the establishment of a geological and natural history 
survey of Wisconsin was not discussed. Two papers dealing 
with geological subjects were presented, abstracts of which 
are here given. 
’‘Origin of conglomerates. G, L. Collie, of Beloit College. In recent 
years authors have attributed many beds of conglomerates to glacial ac¬ 
tion, either directly or indirectly. This idea was first advanced by Rev. 
J. G. Cumming in 1848. The present paper aimed to show that there is 
no direct proof of ice action in conglomerate beds. Conglomerates origi¬ 
nate in one of several ways: 1. By the breaching action of waves upon 
exposed rocky coasts. 2. By the disintegration of land surfaces and the 
removal of the harder portions of the debris to the sea, illustrated by 
Cambrian conglomerates in the Green mountains. 3. By the accumu¬ 
lation of pebbles in talus slopes, illustrated by the Ococe conglomerate, 
the Bishop Mountain conglomerate and the Siwalik conglomerates of 
India. 
The conglomerates above enumerated are true basal conglomerates, 
being made up of debris derived from neighboring terranes. There is a 
class of conglomerates, not basal, that lie upon rocks from which they 
could not be derived. The author discussed this group, taking as a 
typical example the Pottsville conglomerate and showing that it was de¬ 
rived from a number of different points of origin, that it could not be a 
continental glacier that was concerned in its production, the mode of 
occurrence being too irregular and erratic for such an origin. Much 
of the material was derived from the south, not from the north as might 
be expected if glacial action were concerned. The conglomerate be¬ 
comes very thick about certain centers and rapidly thins on passing 
away from these centers, thus showing that their derivation was local. 
The paper closed by stating that the ordinary agencies at work to-day 
are sufficient to account for conglomerates and there is no need to call 
in the aid of extraneous agencies. 
Some stages in the development of rivers as illustrated, by the Deer 
river , Michigan. J. Morgan Clements, of the University of Wiscon¬ 
sin. The Deer river flows in a south-southeasterly direction through a 
pre-glacial valley which was not entirely obliterated by the deposition 
of the drift. The drift barriers formed across the valley as the ice re 
