SECT. 1] 



THE CRUSTAIi ROCKS 



Table II 

 Eastern North Atlantic 



95 



« Anomalous value omitted from averages and standard deviations. 



in the Atlantic as in the Pacific, and Hill (1957) beheves that there is no con- 

 vincing evidence of its absence. Ewing and Press (1955) are doubtful of its 

 universal presence. 



At some of the stations at which Layer 2 was not directly observed by 

 bottom refraction, there w^as indirect evidence for its existence. One piece of 

 evidence comes from the reflection times of strong sub-bottom reflections. If 

 these reflections are assumed to come from the base of the unconsolidated 

 sediment, the sediment thickness estimated thereby is often less than that 

 calculated from the refraction data in the absence of Layer 2 (Ewing and 



