Ch. 34] 



AIRFIELD SITING AND CONSTRUCTION 



651 



become aware in detail of the problems to be faced. The geologist, 

 in his reconnaissance report, should include the following information: 



(1) Description of the ground to a depth of 5 to 10 feet, behavior of 

 subsoil water, and influence of atmospheric precipitation on the firm- 

 ness of the ground surface. 



«<r>njrf' Escarpment 



^H|^ Hilly and mountainous 

 ^HHH area as shown on 

 ^^^ Hydrographic Office Chart 



Fig. 3. Airfield-siting map of Guadalcanal Island prepared in July 1942, one 

 month before the landing. Areas 10 and 11 were classed as the most suitable for 

 airfields and areas 8 and 9 as less satisfactory. The stars indicate airfields con- 

 structed on the island after the landing. The airfield at the west is Henderson 



Field. 



(2) Description of the general stability of the area: landslips, cave- 

 ins, cavernous formations. 



(3) Possible construction materials and recommendations for de- 

 velopment of gravel pits or quarries. 



Most airfields are built on flood plains; therefore not only drainage 

 but flooding also must be carefully considered. Height and fluctuation 

 of the water table must be determined in detail ; the regimen of nearby 

 streams must be known so that flood-prevention measures may be pre- 

 pared. 



As has been mentioned, many natural materials, including coral 

 and "laterite," have been successfully used as airfield surfacing. In 



