802 General Notes. ` [September, 
rea, Metoptoma, Ophileta, Pleurotomaria, Hyolithes, Serpulites, 
Amphion, Bathyurus and Ogygia, are better represented in the 
Middle Cambrian. Discina, Pleurotomaria, Amphion, Bathyu- 
rus and Ogygia are doubtfully referred to the Cambrian. Several 
other genera pass up into the base of the Lower Silurian. 
GEOLOGICAL News,—General._—M. Jelsky (Bull. d. 1. Soc. Geol. 
de France. 1885, 581,) brings forward concerning the origin of 
earthquakes and the lifting of mountain chains a theory to some 
extent new. Postulating a liquid interior and the constant sink- 
ing of the heaviest portions of the crust, which he believes to be 
the ocean bottoms, he shows that the sinking cannot be perfectly 
uniform, since a solid always bears much compression before it 
yields, and asserts that the sudden sinking must producea plutonic 
wave on the surface of the liquid interior. Under the conti- 
nents cavities probably exist, caused by the lifting of the crust by 
former plutonic waves which, when they sank, left a space be- 
neath the crust their movement had raised. When an earthquake 
is produced by sinking of the sea-bottom, it may (1) spread itself. 
over a vast area if it is propagated to a broad sub-continental 
cavity ; or (2) it may produce a volcanic eruption; or (3) it may 
lift a portion of the neighboring continent. e presence of vol- 
canoes is thus attributed to the pressure of the plutonic wave, an 
this explains the frequency of volcanoes in non-continental re- 
gions, or near the sea-margins, where there is no extensive cavity 
below. The perpetual waste to which a continent is subjected 
must finally cause its ruin; the vault becoming so thin that it 
breaks at the shock of a great plutonic wave. The recoil of the 
wave, aided by the weight of the broken vault, will cause the ele- 
vation of a portion of the sea-bottom and the formation of a new 
mountain chain, while the sea, rolling toward the sinking part, 
aids the change by the transference of its weight. Professors 
Romanovsky and Moushketoff have issued the first of three vol- 
umes upon the geology of Turkestan. From this it appears t we 
nearly the whole of the Aral basin, including the wide tracts, east 
and south-east of the lake, is covered with chalk; the remaining 
twentieth being occupied by crystalline unstratified rocks, meta- 
morphic slates, and Paleozoic deposits, all the hills rising above 
the steppes being Archzan or Palzozoic. Jurassic deposits a) 
on the Baidam and Saram rivers, on the borders of the East 
orn life-remains. The Eocene deposits consist for the most 
art of deep-sea Nummulitic sandstones, and are covered by Oligo” 
cene and Miocene, showing by their fossils a gradual shallowi0s 
" me ses. The P 
of tee oes ost-pliocene deposits, which extend from the 
