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Large well developed rock flat which appears
and forms
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is
the inner beach-face in that locallty.
BRUCE,
7
Atoll,
parts:
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at the northernmost end of ELMER
a smaller islet,
is located at the extreme eastern edge of Eniwetok
about 5 miles north-northeast of ELMER.
the larger part,
end of the islet;
This
roughly square in shape,
the smaller part,
comprises
end.
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The erection of several measuring
installations has not to any great extent affected the natural topography of the
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.
is situated at the southern
BRUCE is approximately 0.4 miles long by 0.2 miles wide and contains less
than 0.1 square statute miles of dry land,
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the entire northern
an irregular narrow strip separated from the
main islet by a water-filled depression in the reef,
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iglet has two principal
islet.
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As will be seen from Figure 9,
the islet consists of an essentially flat
4
7
table-land which occuples the entire central portion of the islet and is about
1
12 feet above sea level.
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gently downward from its seaward edge toward the lagoon, are several small dune-
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Along the lagoon side of this table, which slopes
like mounds which reach elevations of 13 to 15 feet.
taken on BRUCE,
including the traverse observations,
Most of the observations
were obtained in the
vicinity of an abandoned steel-mat airstrip which runs across
;
7
of the islet as shown in Figure 9.
ii
the central part
This airstrip has been abandoned for five or
gix years and is now covered with a growth of grass and weeds but as yet has not
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been over-grown by heavier brush,
The sea reef comprising the eastern edge of BRUCE is characterised by the
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extensive development of lines of groins or rock bars,
edge.
transverse to the reef
The reef itself may be divided into five zones:
which slopes gently seaward with no buttresses apparent.
74
(1)
The Algal Ridge
This zone is approxi-
mately 80 feet wide with numerous surge channels in the form of widely spaced
.
cracks 1 to 4 feet wide and 1 to 5 feet deep that extend 50 feet or more beyond
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the ridge crest.
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The channel walls are straight-sided and smooth;
eroded algal limestone,
the floor is
its surface wavy and bare except for sparse gravel and
boulder nodules in shallow potholes.
The crest of the ridge is gently rounded
and lies a foot or more above low water.
(2)
The Algal Pavement consists of a
flat pavement of Porolithon, mostly yellow and dying, under one foot or more of
water.
The pavement is about 66 feet wide.
(3)
The Reef Flat is of orange-
yellow algal limestone veneered by a thin film of Foraminiferal sand and marine
algae.
The flat surface is barren and covered with 2 to 6 inches of water.
12
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