Midocean Approximations
185
Recall that Zn is the interface at the top of the nth density layer. The
solution of (4.3.7) subject to the condition that the dynamic correction to the
pressure vanishes below the deepest moving layer for which n = N, is
N
nn = - LY;Zi+i·
i=n
( 4.3.8)
In the layer model which allows outcropping to occur, the number of
active layers differs from location to location, as shown in the schematic in
Fig. 4.3.1. If M is the index of the upper most layer at the geographical position
under consideration:
n
Zn+i = - Lhi.
j=M
( 4.3.9)
Therefore, the dynamic pressure can be written, aside from an irrelevant
constant, at any location in terms of the layer thicknesses as:
(4.3.10)
Fig. 4.3.1. Schematic presentation of the layer model. At the location indicated (vertical dotted line)
the uppermost layer is layer M. The lowest moving layer is layer N. The index M changes from one
geographic position to another and in general decreases southward