VII, CONCLUSIONS 



Concluding remarks deal with two separate phases of the study. The 

 first six items summarized below deal with the development of field tech- 

 niques; the remaining items deal with geologic interpretations resulting 

 from this study. 



1. A seismic refraction study should precede the drill-hole study if 

 both are to be done. 



2. Drilling equipment that is capable of reaching the deepest bedrock 

 regardless of the nature of the overburden should be selected. 



3. A high explosive should be used as the seismic energy source to 

 avoid signal attenuation. 



4. Preliminary time-distance plotting should be done in the field 

 using a nomogram solution to gain an accurate judgement about the 

 location of future profile lines. 



5. Dunes or large accumulations of dry sand should be avoided when 

 running seismic profiles. 



6. Shallow-refraction seismic methods are successful near the shore 

 if attention is given to the following problem areas: 



a. The "blind zone" due to a second layer of intermediate velocity. 



b. The non-zero intercept due to a dry layer between the surface 

 and the water table. 



c. Apparent sediment velocities due to thickening or thinning of 

 a low-velocity layer. 



d. Attenuations of seismic energy in a layer underlain by peat. 



e. Apparent bedrock velocity due to either a highly irregular 

 surface or a steeply dipping surface. 



7. Seismic and drill-hole results suggest a well-defined bedrock 

 surface. Bedrock topography is highly irregular and varies from 

 surface outcrop to depths in excess of 150 feet. Mantled on this 

 bedrock surface is till and many Pleistocene topographic highs. 

 This Pleistocene topography can be inferred largely from the modern 

 drumlin configurations, although some glacial topography has been 

 reworked by the sea or buried by coastal deposits. 



8. Deposited on this glacial drift is a thick layer of glaciomarine 

 clay. The clay, of nonuniform thickness, appears to cover most 



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