346
T. BELT ON THE STEPPES OE SOUTHERN RUSSIA.
surface modification of the fine diluvial clay, produced by the pene-
tration of roots carrying down organic matter.
About eleven miles north-east from Taganrog, at the village of
Siniafka, the following section (fig. 3) is exposed near the railway
from Taganrog to Ilostof.
Fig. 3. — Section near Siniafka, 11 miles N.E. of Taganrog.
I31ack soil
Diluvium
10
Fluviatile beds ....
Older SteppeLime- )
stone or Con- C 1°
gerian beds. '
Farmatic or Pas- I jg
sage-beds. J
Covered with talus
Alluvium
of Don.
The lowest strata seen at this place are thinly laminated beds of
dark sandy silt, containing impressions of Tapes gregaria and a few
other shells belonging to the Sarmatic or Passage-beds.
Above these lie about 15 feet of limestone, composed, in a great
measure, of the shells of a species of Dreissena. Some of the lowest
beds were entirely composed of these shells, held together by a little
calcareous cement. The upper beds are sometimes concretionary,
and resemble in appearance some of the magnesian limestones of the
north of England. These limestones are the Older Steppe Lime-
stone of Murchison, and the Congerian or Ingersdorf strata of the
Austro -Hungarian geologists.
Above the limestone lies about 10 feet of yellow sand, which
becomes a little loamy upwards. At the base I found fragments of
limestone and pebbles of quartz and quartzose sandstone. I saw no
shells ; but fragments of bones and of tusks of the Mammoth were
not uncommon. I picked several pieces out of the undisturbed
sand ; and the workmen employed in getting ballast for the railway
had thrown on one side many others.
In ascending the estuary of the Don a similar succession of beds
is often exposed, though one or more members of it are frequently
absent through denudation ; but everywhere the diluvium caps the
series, resting sometimes on the Congerian strata, and sometimes on
the Sarmatic beds. I sketched the following section (fig. 4) near
Nova Tcherkask, the chief town of the Don Cossacks.
The cliff near Nova Tcherkask is mostly formed of the Sarmatic
and Congerian strata, and there is a capping of only about 18 feet