ENVIRONMENT


of St. John resulted in a topographic structure resembling a steep
mountain with an elongated east-west axis. The eastern terminus
of this axis faces the prevailing winds which are constant and
relatively dry. The island, like the inverted keel of a boat, shears
the easterly winds, which for the most part pass on without affecting
the island. During the fall, with winds coming in more from the
southeast and more laden with moisture, a forced lift of warm and
sometimes saturated air takes place. The air will ride up over the
mountain slopes, form cumulo-nimbus clouds, and bring rain to
the summits and northeastern slopes. Often as not, there is sufficient
velocity to the wind to push or lean the convectional clouds north-
west beyond the island, where they drop their rain into the sea.
This pattern of dropping rain on the leeward side is not usual in
the relationship of topography to convection, where it is usually
the windward side that receives the moisture. The island of St.
John, however, is so small in relation to its height and axis that
the reverse action takes place. Actually, it is this delayed action that
results in the south and east portions of the island being dry, while
the north and west coasts and slopes are relatively moist. This, too,
I believe, will prove to have had strong influence on pre-Columbian
settlement placement.
 Stone (1942) has pointed out that there are few adequate rain-
 fall records for this region, and especially St. John. Generally speak-
 ing he notes that September, October, and November are the more
 rainy months, while February, March, and April is the prevailing
 dry season. High temperatures seem to correspond with the rainy
 season, while lowest temperatures are noted during the dry months.
 Stone cites an average rainfall for eastern St. Croix of 25 inches
 or less annually, a figure that would doubtless be higher than
 eastern St. John, where the resultant vegetation strongly reminds
 one of arid stretches of the Southwestern United States and northern
 Mexico. It is the rainfall on the north, northwest, and west of
 these islands that brings the overall average for the Virgin Islands
 to 45 inches annually. Stone also states, "Owing to the small and
 erratic rainfall, the dry porous soils, high evaporation, and the few
 permanent streams, it has been a serious problem to obtain a do-
mestic water supply" (Stone, 1942, 31). This problem would have
been equally crucial to prehistoric settlements.