Ch. 15] GEOLOGIC COLLABORATION WITH ENGINEERS 287 



forming an engineer that a beach deposit is recent in the geological 

 sense., and derived from Quaternary deposits, is not helping the engineer. 

 He will have made a major contribution if instead he can say that 

 the beach deposit was probably made in the last half-century and that 

 the material was derived from sandstone in such and such locality by 

 erosion and stream transportation to the beach. The possibilities of 

 interpretation of geologic information with a view to defining the 

 dynamics of the environment have been realized but slightly. In this 

 field they are particularly rich. 



The geologist is eminently qualified to furnish basic data needed 

 for shore control. Particularly is this true with respect to the definition 

 of physiographic units and the determination of the source and char- 

 acter of littoral material. The engineer must contribute to the geologist 

 knowledge of the forces acting and the nature of their distribution in 

 time and space. Close collaboration between the two professions in 

 the study of these problems will produce results of high economic 

 significance with a minimum of effort. Almost all that is required is 

 a wedding of the static and dynamic analyses now available. 



Another area of collaboration that promises useful results quickly 

 lies in study of the sources and transportation phenomena of material 

 movement. Geologists already are informed about many of the details 

 of the derivation of beach material from source rocks and the resulting 

 characters of the material. Some of the gross details of transportation 

 effects on the materials, for example, selective transportation and 

 rounding, have been explored, chiefly by geologists, but much remains 

 that can be done. The engineer can provide knowledge of some of the 

 dynamic situations to which the material has been subjected, for ex- 

 ample, the mechanisms of bed-load movement and the rate of mass 

 movement of material in various types of watercourses. Here again 

 the study of cause and effect with particular reference to the dynamic 

 processes involved should produce immediately useful relations of value 

 to both the geologist and engineer. The establishment of verified re- 

 lations between material characteristics (including both discrete par- 

 ticles and aggregations of particles) and the dynamic processes in which 

 the material has participated should open possibilities for a much bet- 

 ter understanding of the details of transportation and deposition of 

 sediments. 



Engineers and geologists could well consider collaboration with a 

 view to detailed study of the energy-material relations controlling 

 physiographic changes at the shore. Engineers can supply much in- 

 formation on wave energy, its distribution along the shore and modi- 

 fication with changes in the shore conditions, which, coupled with 



