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t Absence of a clear-cut external charge area of the ground
water.
t Drastic increase in horizontal hydraulic resistance along
the way of ground water infiltration with distance from the
charge zones.
t Decrease in the same direction of vertical resistance,
which transforms the lateral flow into mostly vertical flow
(Vsevolozhsky, 1983; Dyunin, 1965).
The acceptance of the Pliocene complex functioning under a typically
elision regime assumes the corresponding litho-reservoir and tectono-
structural conditions in the stated interval. The Pliocene is the region char-
acterized by:
t Drastic increase in clay content down the regional dip
toward the central part of the South Caspian (the Apsheron
area 35-40 to 70-75%, the Djeyranchekmes Depression and
Baku Archipelago 75 to 95%, the Lower Kura Depression 65
to 85-95%, the Balkhan area 50-65 to 95%).
t Due to increase in clay content, noticeable deterioration of
reservoir properties, increased dispersion of clastic material,
increase in the content of silt and clay fractions, decrease in
clearance (plane porosity) and growth in sinuosity of the
pore channels.
t Decrease in thickness and sequential pinch-out of the sec-
tion intervals from the basin's center toward its periphery,
thus the formation of dead-end hydrodynamic areas (see
Figure 1.2).
t The development of mostly clay facies in the central portion
of the South Caspian, i.e., its lens-shaped outlook.
All these positions present the Pliocene in the region as an interval
where any significant ground water flow from the basin center to its flank
zones is restricted. Another serious factor hampering water flow in the
stated direction is its non-Newtonian behavior in the finely-dispersed low-
permeability volumes of the section with insignificant regional hydraulic
grade (Bondarenko, 1973; Valukonis and Khodkov, 1973; Gurevich, 1969;
Khodkov and Valukonis, 1972).
When discussing the ground water flow in the region under elision
regime, it needs to be kept in mind that clay permeability is lower by sev-
eral orders of the magnitude than the other rocks in contact with clays. The
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