T/ios. Belt — The Steppes of S. Russia. 
369 
at explosive foci,” which he 6 kl not think could be carried back 
much beyond the Tertiary epoch, the author discussed the ordinary 
method of formation of a volcanic cone, and pointed out that the 
effect of the piling up of material must produce a pressure on the 
original surface commensurate with the amount of material heaped 
up on it, and therefore increasing gradually from the circumference 
nearly to the centre of the cone, where the loftiest colurnn of material 
presses upon the unit of space. When the supporting rock is un- 
yielding, such as the granite which bears the Puys of Auvei’gne, it 
will probably maintain its original position ; but when it is of a 
more yielding nature, as in the case of the ordinary stratified rocks, 
the pressure of the cone will produce a saucer-shaped depression, 
deepest in the centre where the greatest pressure occurs ; and this 
tendency to sink will be aided materially by the honeycombing and 
evisceration of the subjaeexrt rock-masses exposed to the action of the 
volcano. The consequence of this depression of the surface support- 
ing the cone will be to diminish the original slope of the successive 
superimposed deposits, and even in some cases cause the lowest beds 
to slope from the circumference towards the centre. If the strata 
upon which the volcano Stands be particularly plastic, its pressure 
may cause an uprise of the strata into protuberances round the foot 
of the mountain. Similar phenomena may occur when the Support 
of the cone is formed by older volcanic deposits. 
2. “ The Steppes of Southern Russia.” By Thomas Belt, Esq., 
F.G.S. 
The author describes seetions of strata in the south of Russia, and 
traces the following succession of events : 
1. Deposition of marine Miocene beds when the Yienna basin and 
the Aralo-Caspian area were joined together, and had free commu- 
nication with the Mediterranean. 
2. Interruption of the communication with the Mediterranean, and 
deposition of the Sarmatic beds in a closed sea-basin. 
3. Gradual fresliening of the water of this area and deposition of 
the Congerian strata. 
4. Lowering of the water of the Yienna basin and Aralo-Caspian 
area to below the present level of the ocean, and great denudation 
of the preceding strata. The author thinks that the drainage was at 
this time to the north. 
5. Interruption of drainage to the north and deposition of fluviatile 
beds, with freshwater skells of existing species and remains of the 
Mammoth and Irish Elk. 
6. Drainage to the north completely stopped and formation of a 
great lake, over which floated icebergs with northern drift. Forma- 
tion of diluvial clay of the south and boulder-clays of the north of 
Russia. 
7. Lake gradually lowered by the cutting througk of the channel 
of the Bosphorus. 
The author considers that the formation of the great lake was due 
to the ice of the glacial period flowing down the beds of the Atlantic 
and Pacific, and damming back the drainage of the continents as 
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DECADE II. — VOL. IV. — NO. VIII. 
