STRATIGRAPHY OF THE DEEP-SEA FLOOR 65 



(Weatherby and Faust, 1935; Faust, 1951) that there is a definite 

 relationship between age and Hthification ; older sediments have 

 had a longer time to be altered by chemical actions. 



After a calcareous ooze has been lithified to limestone, it has a 

 strong, rigid structure. It is unlikely that further deposition caus- 

 ing increasing overburden pressures would cause any marked re- 

 duction in porosity. Porosities in limestones should decrease owing 

 to chemical changes, but the marked reduction of porosity be- 

 cause of depth, so well known in shale, will not occur. This is 

 borne out by depth-porosity diagrams in limestone from oil well 

 data (Wyllie et al., 1956; Hicks and Berry, 1956). These factors 

 allow relatively low porosities in rock near the surface having little 

 to do with pressure-induced consolidation. Tables I and II and 

 Figs. 1-5, therefore, are merely suggestive and do not illustrate 

 expected porosities at depth for lithified calcareous material. The 

 transition between cemented and uncemented material is likely 

 to be relatively sharp, not gradational. 



In the deep sea, including seamounts, but excluding the coral 

 atoll environment with its coralline algae and coral, the known 

 occurrences of Joraminiferal limestone are rare. Murray and Lee 

 (1909, p. 22) recorded three instances (one each by the Albatross, 

 Challenger, and Britannia) when hardened Globigerina ooze \\'as 

 dredged from the sea floor. The Scripps Institution — U. S. Navy 

 Electronics Laboratory Expedition in 1950 dredged indurated cal- 

 careous ooze in the form of foraminiferal limestone from four sea- 

 mounts in the mid- Pacific Mountains west of Hawaii and from 

 one seamount in the northern Marshall Islands. The geology and 

 paleontology of this material is described in detail elsewhere 

 (Hamilton, 1953, 1956; Hamilton and Rex, 1959). Five samples 

 (cf. Fig. 6) examined in great detail (including determinations of 

 the velocity of the compressional elastic waves) are very important 

 in considering the possibility that normal sedimentation can ex- 

 plain part of the present concepts of sea floor structure based on 

 seismic studies. The grain densities (plus other studies) indicate 

 that some of the material has been phosphatized ; porosities ranged 

 from 5 to 68% and velocities ranged from 1.77 to 5.46 km/sec at 

 room temperature and pressure (Table HI). In short, we would 



