54 SMITH 



(5) Unless blended with coarser sand, it is unsuitable for concrete aggregate, but is 

 suitable for bituminous surfacing. 



(6) Special protective measures against sand drifting are necessary where the surface 

 is bare. 



(7) Stabilized surfaces readily revert to drifting if improperly handled. 



Dune topography also has the follow^ing surface characteristics which are significant for 

 military operations: 



(1) Dune ridges and blowout hollows offer good cover from ground fire, and the nature of 

 the sand tends to muffle and restrict the effects of bombs and shell fire. 



(2) Dunes commonly provide excellent concealment from the ground view. 



(3) In many coastal areas high dunes provide the best available observation points. 



(4) Special camouflage methods, such as simulated blowouts, might be adapted to dune 

 areas. 



(5) Tracks of men and vehicles on bare sand are quickly obliterated if the wind is blow- 

 ing strongly, and the same effect probably could be obtained by airplane propellers or helicopter 

 rotors. 



(6) Actively blowing sand introduces special maintenance problems for equipment. 



(7) The readiness with which stabilized dune sand reverts to the actively blowing condi- 

 tion introduces an additional factor in planning operations or installations, and offers a possible 

 means of harassing enemy-held coastal territory. 



(8) Bare dune sand provides poor footing for men and for wheeled vehicles with ordinary 

 equipment, but offers fair to good trafficability for tracked vehicles or for wheeled vehicles 

 with 4-wheel drive and oversize, low-pressure tires, within certain limitations of slope. 



(9) Stabilized sand surfaces under certain conditions offer good trafficability initially but 

 tend to deteriorate rapidly if traffic continues. 



(10) In swampy areas, dune ridges may provide the best available trafficability. 



(11) Various types of dune topography provide innumerable combinations and patterns of 

 channels and obstacles for movement. Where the dunes are strongly asymmetric, movement 

 may be a one-way proposition. Movement toward inland points is facilitated by some types of 

 dunes and greatly retarded by others. Knowledge of the general types of dunes present permits 

 rapid appraisal of the possibilities for movement. 



CONCLUSIONS 



Dune topography constitutes one important type of coastal terrain, and has certain special 

 characteristics that play an important part in the planning and execution of operations in the 

 areas concerned. Some of these characteristics are essentially the same for nearly all types 

 of dunes, whereas others are more individualized and more specifically gr>verned by local 

 conditions. Proper appraisal of the latter must be based on continued research on the geogra- 

 phy and geology of a wide range of representative areas, in as many different types of environ- 

 ment as possible. Such studies may be expected to make for more rapid and efficient procure- 

 ment of terrain intelligence for those coastal areas where dunes occur, by air-photo interpre- 

 tation or by other procedures. It is hoped that the project here represented will contribute to 

 that general objective. 



