ENVIRONM FNT


when native boatsmen would have encountered tide floods that
would have influenced their areas and patterns of movement. For
example, during tidal flood in this region the flow is southeastward
or against the windward for 6 hours prior to moon transit, while
the ebb sets to the northwestward for 6 hours after moon transit.
To complicate the navigational problems around these islands,
there is also a seasonal predominance of the southeastward flow
from mid-June to mid-August. Local fishermen refer to the initial
stages of this set as the "St. John's Tide," for the current holds
8 to 10 days to a continued southeastward flow-a forceful flow
against the wind. Despite these occasional variations and local
tidal changes, the general movement of water is strong through the
islands from the east to the west.
 Those natural actions of the sea that undoubtedly affected the
native boatsman and the location of his settlements to the greatest
degree in the St. John and Virgin Island group were the swells,
rollers, and associated shore flooding. This whole region is con-
stantly under the influence of the northeast and east trade winds;
therefore, it is from the northeasterly, easterly, and southeasterly
directions that the islands are buffeted by seas and swells through-
out the year. It matters not whether the native peoples are in
Polynesia or the West Indies; the proper placement of settlements
will be predicated on security from wind and sea. It is necessary
that seaside settlements have all-weather beaching ability, and it is
also necessary that villages be protected from storm and flood
damage. In due time, the aborigine would have experienced these
natural forces and would have adjusted to them.
 Without a doubt pre-Columbian peoples witnessed here, as
have modern observers, a great sea wave called tsunamis. This type
of wave results from an earthquake or volcanic explosion. The
smashing waves often arrive without notice, but are usually her-
alded by a withdrawal of waters along the coast or bay. An inter-
val of 30 minutes to an hour may elapse between this withdrawal
and the great onrush of waves. This pounding of shore areas can
go on for as much as one or two days, and if a native settlement
were built close to the sea, it could have been badly wrecked. The
Hydrographic Office reports that tsunamis of varying destructive
force may be expected in the West Indies on an average of 1 in
12 years.