investigations. NEL received samples for investigations 

 of shear strength, consolidation, sound speed, and related 

 properties. These sediments are the deepest ever taken 

 from the deep-sea floor and consequently afforded a unique 

 opportunity to define the variations of the sediments and 

 their properties with depth in the sea floor. This section 

 concerns measurements of sound speed and related prop- 

 erties of sediments from Guadalupe Site Hole No. 3 (EM-8), 

 hereafter referred to as "Mohole sediments" or "the drill 

 hole." Other NEL reports concerning these samples are 

 by Igelman and Hamilton, Moore, and Hamilton. 9 ' 25 ' 2S 



The deep-sea floor east of Guadalupe Island is gently 

 undulating and the surface sediment is deep-sea ("red") 

 clay, 27 underlain by "hemipelagic" greenish-gray silty clay 

 which could be broadly classified by its constituents as a 

 calcareous-siliceous ooze. The drill hole was at 28° 59' N. 

 117° 30' W., in a water depth of 11,672 feet (3558 m; fig. 3). 

 The drilling operations have been fully described and much 

 information has been published concerning the sediments in 

 the hole and the basalt cored at a depth of about 56 feet 

 (170 m) beneath the sea floor. 28 ' 29 After the drilling oper- 

 ations, additional reflection surveys have shown the basalt 

 surface to be at varying depths below the water-sediment 

 interface. 3 



26 



