THE QUATERNARY CASPIAN. 25 
descends into the Caspian. Here a t>'pical section shows anticlinal and monoclinal 
Aralo-Caspian ridges, with strata dipping 20° or 30°, and crests rising from 600 to 
800 feet o\er the present Caspian level. The existing Caspian is by a still greater 
measure of time separated from that ancestral water body in which the Akchlag^l 
strata of the Ust-urt plateau as described by Andrussof (1902) were laid down, these 
being pre-Pontic and post-Sannatian. The Tertiary seas represented by the 
Sannatian and Mediterranean stages (Miocene) were yet more ancient. Their 
deposits are so widely distributed on existing lands and so much deformed and 
eroded that their parent waters had little resemblance to the seas of to-da\-. 
The Quaternary Caspian, with whose shorelines and deposits we are concerned, 
is more modem than the latest of the seas above named. It does not seem to have 
been the immediate successor of the expanded Tertiar\' seas, for although Neumayr 
thought that there had been a progressive diminution of water area from Sannatian 
times, not interrupted by expansion even during the glacial period (1875, 32), 
Andrussof sa)s that at the end of the Tertiary- the Caspian was probably lower 
than at present (1888, 113). Our observations confinn the latter view. There 
must have been indeed a considerable period of late Tertiar\- or early Quateman' 
time when the Caspian had a lower level than now, for not only the high-le\-el 
Quateman,- shorelines, but even the present Caspian shorelines, contour around the 
eroded ridges of the deformed (Tertiar\) Aralo-Caspian strata at Baku. The low- 
water epoch between the Tertiar}- and Quatemar}- periods of Caspian expansion 
nmst have endured for a much longer measure of time than that of the Quatemar}- 
high-water stage and the present mid-water stage, taken together ; for the erosion 
that the defonned (Tertian) Aralo-Caspian strata suffered before the Quatemar\- 
Caspian rose upon them at Baku is hundreds of times greater than the sum of the 
erosions recorded in the Quatemar)- strands, and thousands of times greater than 
the erosion that the strands have suffered since the waters retired from them. It is 
also important to note that the historic oscillations of the Caspian are all short-lived 
events, and that their order and rate of change can not be safely used to determine 
the time since the high-level Quatemar}- shorelines were occupied. 
The Quatemar}- Caspian appears to have been confluent with the Aral on the 
east, as will be more full}- stated farther on ; hence the tenn Aralo-Caspian has been 
applied to this expansion of the sea as well as to that of late Tertiar}- time ; and it 
is not always easy to understand which sea is meant when this ambiguous name is 
emploved. The Quatemar}- Caspian was also confluent with the Black Sea, for its 
strands are hundreds of feet above the existing water level, while the pass between 
the two seas in the Man}-ch depression north of the Caucasus range is only 26 
feet over the Black Sea, and 112 feet over the Caspian. It is indeed eminently pos- 
sible that the confluence of the Caspian and Black seas may have taken place at 
the time when the Bosponis was a nonnal river ; hence our passing sight of this 
beautiful water passage was of peculiar interest in connection with our later 
observations farther east. 
