. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 42 ANNALS OF THE SOUTH AFRICAN MUSEUM - | A 12- GRAVEL ^ A SAND weight % / • \ • \ 8- / \ / \ • 4- / \ CIRRIPEDS \ • 0- i i i i -3 -2 - l i i i I i 1 0 +1 4-i .-, B / \ • \ J 2- / \ • \ BRYOZOANS V i i i i -3 -2 - 1 0 +1 31 2- 1- in V MOL 'Y LUSCS • iii -3 -2 -1 1 I ' i ' 0 +1 1-1 D ECHINODERMS 0,5- \r\ J\ v. 1 I i 1 1 1 i i « i -3 -2 -1 0 +1 0,4 0,2 CORA LS X r4^-, ~i—I—i—r ?3 -2 -1 0 +1 0,2-, 0,1 QUARTZ 1—i 1 ' / N • / 1—r 0,2n 0,1 0 -3 -2 -1 0 +1 n—i—i—r 3 -2 -1 0 +1 phi-units Fig. 8.
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 42 ANNALS OF THE SOUTH AFRICAN MUSEUM - | A 12- GRAVEL ^ A SAND weight % / • \ • \ 8- / \ / \ • 4- / \ CIRRIPEDS \ • 0- i i i i -3 -2 - l i i i I i 1 0 +1 4-i .-, B / \ • \ J 2- / \ • \ BRYOZOANS V i i i i -3 -2 - 1 0 +1 31 2- 1- in V MOL 'Y LUSCS • iii -3 -2 -1 1 I ' i ' 0 +1 1-1 D ECHINODERMS 0,5- \r\ J\ v. 1 I i 1 1 1 i i « i -3 -2 -1 0 +1 0,4 0,2 CORA LS X r4^-, ~i—I—i—r ?3 -2 -1 0 +1 0,2-, 0,1 QUARTZ 1—i 1 ' / N • / 1—r 0,2n 0,1 0 -3 -2 -1 0 +1 n—i—i—r 3 -2 -1 0 +1 phi-units Fig. 8. Size distribution of individual component groups. utilizing the method of Rankine (Zenkovich 1967). Figure 10 presents a theoretical velocity vs. depth diagram for deep water waves with periods between 5 and 15 seconds and heights from 1 to 10 metres. Not shown in the diagram are the various frequencies at which these individual waves occur since they might change from place to place. For South African waters frequencies for wave heights and zero-crossing periods were calculated for the depth ranges 0-15 m and > 15 m using data compiled by Darby shire & Darbyshire (1964), Darbyshire & Pritchard (1966) and Shillington (1974). The 15 m division line was chosen because it demarcates the observed abrasion base in this area. Two threshold velocities were arbitrarily selected from the empirical data of Hjulstrom (1935), modified by Sundborg (1956), and modified by Allen (1965).. 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 South African Museum. Cape Town : The Museum
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
