As indicated previously, a variety of soil conditions was encountered.
The soils of Eniwetok Atoll are basically similar to those of other islands
in the Ralik Chain of the Marshall Islands.
Held and others have commented
on these soils for several atolls.3
"The parent material is primarily calcium carbonate,
originating from corals, foraminifera, coralline algae and
mollusk shells... In some areas, particularly along the
seaward side of the islets, buried... horizons are formed
as deep as 80 inches.
These highly organic horizons presumably
result from storm debris covering previously established soil
and vegetations."
Although these remarks, describe the relatively pristine conditions of
Rongelap Atoll, they are certainly applicable to the majority of islets on
Eniwetok Atoll.
Modified conditions are found, as expected, on these islands
on which testing and/or construction were conducted.
Soil profiles observed on most of the islets consisted of a surface layer
of vegetative litter of varied thickness followed by a somewhat thicker layer
of dark coral soil containing some root structure, and other organic material.
This layer also varied in thickness, being thicker on undisturbed islands and
thinner or absent on disturbed islands.
This second layer was usually followed
by the basic coral sand structure of the island which prevailed down to the
hard coral limestone bedrock.
Buried horizons were. found at almost any depth.
Coral fragments of nearly any size infiltrated the soils and could be encountered
almost everywhere.
The vertical distribution of radioactivity in coral soils has been the
Sr. Eg. Held, S. P. Gessel and R. B. Walker, ATOLL SOIL TYPES IN RELATION
TO THE DISTRIGUTION OF FALLCUT RADIONUCLIDES, University of Washington, August
\
1965, UNFL-92 (TID-4500)