. The Earth beneath the sea : History. Ocean bottom; Marine geophysics. 224 BULLABD [chap. U are only roiiglily known but a uniform reduction in conductivity by 4% should avoid serious systematic error. The relation (3) then becomes R = 168 + 678z^;. (4) The conductivity that is required in the calculation of heat flow is the reci- procal of the mean resistivity. Since the resistivity is linearly related to the water content it may be found from the mean water content. The water content at a point in a core may vary from about 25 to 60%, but the mean down a core is much more uniform. For examp
. The Earth beneath the sea : History. Ocean bottom; Marine geophysics. 224 BULLABD [chap. U are only roiiglily known but a uniform reduction in conductivity by 4% should avoid serious systematic error. The relation (3) then becomes R = 168 + 678z^;. (4) The conductivity that is required in the calculation of heat flow is the reci- procal of the mean resistivity. Since the resistivity is linearly related to the water content it may be found from the mean water content. The water content at a point in a core may vary from about 25 to 60%, but the mean down a core is much more uniform. For example, 10 cores of Globigerina ooze from the north-eastern basin of the Atlantic all had water contents between 48 and 40% and mean conductivities between and cal/cm sec °C (Bullard, 1960). 7001- 600 U u 0) E u V u c 500 400 300 200 100. 20 40 60 Water content (per cent wet weight) 80 100 Fig. 5. Relation between thermal resistivity and water content. O red clay, # Globi- gerina ooze, X mud. To calculate the thermometric conductivity, kfap, the densit}^ p, and the specific heat, a, of the sediment are required. If the sediment can be regarded as a mechanical mixture of particles of mean density ps, the spaces between \\'hich are filled with water of density p^, its density is given by 1-1 — ps~^+{pw~^-ps''^)w. Naturally, the best value for ps varies with the type of sediment. A least squares reduction of the 44 densities given in Bullard (1956) and Bullard and Day (1961) gave g/cm^ for Globigerina ooze, for red clay and for mud; all the data combined gave with a standard deviation of 3%. If this accuracy. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hill, M. N. (Maurice Neville), 1919-. New York : Interscience Pub.
Size: 1938px × 1289px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectoceanbottom
