Boston Meeting of the Geological Society. 11 f> 
sets forth some observations of the author made in connection with his 
work as geologist of the U. S. Geol. Survey. One of the noticeable fea- 
tures of beach sands is their endurance to the beating of the waves. 
Pebbles wear at a very rapid rate. The sands of a beach are held apart 
by a film of water, which protects the sands from mutual abrasion. Pro- 
fessor Shaler concludes that from this circumstance arises the protec- 
tion which sand beaches afford the land areas against the assaults of 
the waves. The absence of sand beaches on small islands is attributed 
to the lack of sufficient material eroded from cliffs to make considerable 
accumulations of that nature. The sands of beaches are augmented by 
the action of large sea-weeds, which transport pebbles and strand them 
on the beach. Shells are also borne in from the bottom in the same 
way. Floating pumice is also contributed to the sea-beaches, particu- 
larly on the Florida coast, the amount diminishing toward New Eng- 
land. 
Dune sands are often found with a dry surface in a few hours after a 
heavy rain. Professor Shaler has observed that after a summer rain- 
fall of an inch the dune sand would often not be wet for more than 
three-forths of an inch from the surface, below which layer the sand 
was quite dry, water not being met with until some feet down in the 
mass. This phenomenon is explained as due to the repulsion of the 
water by the dry sands and to the greater ease with which the water 
flows down the slope through the wet crust until it reaches the bottom 
of some depression in the dunes, where it percolates downward through 
the mass. Owing to this shedding of rain, dunes may become dry in a 
few hours after a rain and be excavated by a strong wind. 
The material of dunes where it has remained in repose for years is 
subject to solution and decay, as is shown by much tine dust; which is 
absent in recent dunes and beach sands. The tine dust is blown away 
in the march, and thus hinders the advance of the dunes by diminish- 
ing the amount of the material left in the hills. The decomposition in- 
dicated by the dust serves in another way to check the advance of the 
dunes by fitting the surface to sustain plant life, particularly the 
grasses. Organic matter derived from the beaches acts as a decompos- 
ing agent, and this decay is rapidly promoted by the vegetation growing 
on the dunes, so that the distance to which a dune can travel in ordi- 
nary climatal conditions is never very great. 
V.). The eastern boundary of the Connecticut Triassic. W. M. Da- 
vis, Cambridge, Mass., and L. S. Gkiswold, Dorchester, Mass. After 
illustrating the general structural features of the Triassic belt by a 
series of lantern slides, the authors maintained that the eastern bound- 
ary of the formation, where it adjoins the crystalline plateau, is defined 
by a series of faults, whose existence is proved as follows: Different 
members of the formation successively terminate along the eastern bor- 
der; in passing northward from the sound near East Haven, to the Con- 
necticut river near Middletown, the lower sandstones, the anterior trap 
sheet, the anterior shales, the main trap sheet, the posterior shales and 
sandstones, the posterior trap sheet and the upper sandstones and con- 
glomerates, all gently undulating in northeast and southwest dips, are 
terminated in alternating succession, without regard to their undula- 
tions, but with remarkably consistent regard for the presumable course 
of the hidden fault lines. This cannot be explained as a result of a 
variable overlap of the several members of the Trias on the crystal- 
lines, for tfie former dip towards the latter. The stratified beds, with 
the conformable lava sheets, must be abruptly cut off along their east- 
ern margin. The margin is marked by a depression, wider open when 
the adjacent rocks are weak, narrow when they are hard; but continu- 
ous all along the boundary. Close to this depression, departures from 
the prevailing dip of the formation are frequent; in one place the de- 
partures amount to an overturn; brecciated masses of sandstone and 
