A Preliminary Report on the 
Soils of Saipan, Mariana Islands^ 
Ralph J. McCracken2 
INTRODUCTION 
The purpose of this paper is to provide a 
preliminary description of the nature of Sai- 
pan soils and their factors of formation. A 
preliminary classification and correlation of 
the soils is presented. Arrangements have been 
completed for publication, at a later date, of 
a complete discussion of Saipan soils in con- 
junction with a series of discussions of the 
geology of Saipan, under the auspices of the 
United States Geological Survey. Laboratory 
analyses of representative soil-profile samples 
are at present under way. Genesis and classi- 
fication of Saipan soils will be discussed more 
fully in the later publication, utilizing the 
results of the laboratory analyses. 
This study demonstrated the applicability, 
with minor modifications, of American theo- 
ry and methods of soil survey to pioneer in- 
vestigations of tropical island groups. How- 
ever, the study indicates the desirability of 
improving nomenclature and of differentia- 
ting criteria of classes of tropical soils in the 
higher categories of the natural system of 
classification. 
The survey reported in the present paper 
is presented as an example of the detailed 
areal soil studies advocated by students of 
tropical soil classification (Kellogg, 1948; 
^ A detailed soil survey of Saipan Island, in which 
the author participated, was conducted in 1949 under 
direction of the U. S. Geological Survey. The present 
paper is a report of this work performed while the 
author was on loan to Military Geology Branch, U. 
S. Geological Survey, and its publication was encour- 
aged by that organization. Manuscript received August 
19, 1952. 
2 Soil Scientist, Division of Soil Survey, Bureau of 
Plant Industry, Soils and Agricultural Engineering, U. 
S. D. A. 
Pendleton, 1948) as one of the next important 
steps .in arriving at a true understanding of 
tropical soils. 
Acknowledgments 
The author wishes to express his apprecia- 
tion to P. E. Cloud, Jr., and R. G. Schmidt of 
the U. S. Geological Survey for providing 
information on geologic and petrographic 
studies of Saipan currently in progress. Thanks 
are due M. G. Cline of Cornell University and 
R. W. Simonson of the Division of Soil Sur- 
vey, Bureau of Plant Industry, Soils and Agri- 
cultural Engineering, United States Depart- 
ment of Agriculture, for critical reading of 
the manuscript and for helpful suggestions. 
GEOGRAPHY OF SAIPAN 
Saipan is located at 15° north latitude, about 
1,500 miles southeast of Japan proper and 
1,200 miles east of the Philippines. It lies in 
approximately the center of the Mariana Is- 
lands, about 150 miles north of Guam, which 
is at the southern end of the chain. 
This 48-square-mile island consists essen- 
tially of a core of volcanic rock around and 
over which limestones have been formed. The 
highest elevation, about 1,550 feet above sea 
level, is a peak on the island’s central ridge, 
which is composed of uplifted limestone. The 
island is predominantly rolling and hilly ter- 
rain with the exception of limestone plains 
at the southern end, on the eastern peninsula, 
and at the northern tip. 
NATURE OF SOIL-FORMING FACTORS 
Parent Materials 
Volcanic rocks and volcanically derived 
rocks (sandstones and conglomerates) of Eo- 
267 
