838 



EBICSON 



[chap. 31 



between 65,000 and 70,000 years ago. If we assume a compromise date of 67,000 

 years B.P. for the top of the flexuosa zone in the five cores, A180-72, A180-73, 

 A180-76, V14-5 and V9-28, we obtain an average rate of sediment accumulation 

 of 3.3 cm in one thousand years. 



B. Cores from the Sigsbee Knolls 



These were taken on or near the tops of some low rises at about the center of 

 the abyssal plain of the Sigsbee Deep in the Gulf of Mexico. The faunal zones in 



Sigsbee Knolls, Gulf of Mexico 

 V3-I27 V3-I28 V3-I26 



Depth 3540 m 3495m 3485 m 



Climatic Variation. <, Coiling of Globo. truncatulinoides 

 SW ^ 24km * l.6l<m ^ ME 



100% Left 100% Right IOO%L 100% R IOO%L IOO%R 



Warm Cold W C W C 



Im 



2m 



3m 



4m 



5m 



6m 



7m 



V, 



\l 



Fig. 3. Cores from the Sigsbee Knolls, Gulf of Mexico. 



the cores are shown graphically in Fig. 3. In this instance time equivalence of the 

 faunal zones is virtually certain in view of the following considerations. At 

 present the deep and open Gulf is homogeneous with respect to coiling of 

 Globorotalia truncatulinoides and the various species of planktonic Foraminifera. 

 It is highly improbable that a faunal boundary could have maintained a position 

 between such closely spaced stations, about 25 km, in so homogeneous a body of 

 water for any appreciable time during the late Pleistocene. 



