useless concept in the United States
(D) The myth of the American free enterprise system
is seriously flawed.
(E) Fascination with the ideal of “openness” has
made Americans a progressive people.
Passage 3
No very satisfactory account of the mechanism
that caused the formation of the ocean basins has
yet been given. The traditional view supposes
that the upper mantle of the earth behaves as a
(5)liquid when it is subjected to small forces for
long periods and that differences in temperature
under oceans and continents are sufficient to
produce convection in the mantle of the earth
with rising convection currents under the mid-
(10) ocean ridges and sinking currents under the con-
tinents. Theoretically, this convection would
carry the continental plates along as though they
were on a conveyor belt and would provide the
forces needed to produce the split that occurs
(15) along the ridge. This view may be correct: it has
the advantage that the currents are driven by
temperature differences that themselves depend
on the position of the continents. Such a back-
coupling, in which the position of the moving
(20) plate has an impact on the forces that move it,
could produce complicated and varying motions.
On the other hand, the theory is implausible
because convection does not normally occur
along lines. and it certainly does not occur along
(25) lines broken by frequent offsets or changes in
direction, as the ridge is. Also it is difficult to see
how the theory applies to the plate between the