Baker Is land- - Geology 
Baker is a reef type island or atoll la which the central lagoon 
has been filled with reef isiateriai and debris. It Is a geologically 
young island, however , still in the growing stage. There is some 
evidence that the volcanic base is still within 100 feet of the surface 
since small amounts of volcanic material have been found on the western 
beach. This material consisted of obsidian, basalt, and vesicular 
basalt (ABC, 1963 )* 
Several auger and core holes drilled to a depth of five to 19 feet 
in October j 1963/ &hm Baker to have a weakly cemented eight to 18 inch 
layer of humus and weathered coral fragments over a complex interheddec 
series of loose coral fragmentsveil graded sands M and coral gravels. 
Also, there was evidence of old hupus-rich soil surfaces of the past 
which are nov buried- In only 
feet below the 
1963 ), 
level, being nine 
sea level. (ABC 
one hole 
surface 
a nd 
water reached * the m 4 « 
approximately 1-5 feet above 
j 
Several large blocks of veil cemented conglomerate found on the 
inland slope of the western ridge were apparently torn from the reef and 
washed ashore by storm waves from the vest 9 and sandstone of fine to 
medium grain vs a found forming ledges on the surface of the reef near the 
low tide line at the southeastern corner. SanJcovers the western and 
southwestern shores while m the eastern shore for a distance of 100 to 
150 feet inland the ground is covered with dark; weathered coral and 
shell rubble of six to eight inch else* The southeastern shore is 
covered with three to five inch weathered finger coral and fragments - 
The interior of Balter has very little humus-rich top soil aw is littered 
with coarse rubble which is believed to have been dumped inland over the 
northeast s 
tde by wave action (ABC, 1963) 
, / 
Baber Island in the late loQO* a was an important source of guano but 
its more valuable deposits have been depleted and the present soils ore 
overwheIniugly sandy, forming only a shallow layer on top of the coral 
conglomerate, which iu places is entirely denuded♦ (Christopherson, 1927} 
The greater part of the interior of Baker Island is covered by a 
light brown sand of an alkaline reaction, dry, a m with © low percentage 
f organic matter* In a few places darker brown, noisier sand with a 
•% 
■’Atf 
higher percentage of organic natter is found. In several placets the 
upper part of the coral conglomerate is partially transformed into a 
brown phoshhate 
_ _-^-giving only a weak reaction for CO- (Ohrlaiopheraon, 
1927}* Chemical analyses of soil and rock samples obtained from different 
parts of the island show little difference iu composition with 'the min 
components being OaO sad CaOg. (AEC, 196:5}* Details m& tables of such 
analyses ore given by Hutchinson (l95Q}> Christophers on (1927); and the 
-«* 
Atomic Energy Oornissiou (l9 : 53) 
Baker Island was worked by the American Guano Ccctpaay from 
r> 
$ i i 
to 
l8?,i and by ieSm I. Arundel and Company from 1886 to 1891 (Bryan, 1982) 
Hutchinson (1950) estimates the original reserve of guano on Baker in 
the neighborhood of 250,000 to 300,000 tons. Hague (1862) describes 
