318 



BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



here, his later discussion in his paper on the Glacial-control theory 

 may be consulted. 1 Daly says: 



"Since probably not more than 5 m. to 25 m. can be allowed for the thickness of 

 the post-glacial calcareous veneer in the wider lagoons, the accordance of platform 

 depth for the wider lagoons and reefless banks seems clear. Their range of 60-90 m. 

 represents magnitudes of the same order as the depths computed for the Pleistocene 

 wave-formed benches." 



I have pointed out the similarity in the depths on Saba, Pedro, 

 and Rosalind banks, to those on the atoll-lagoon floors of the Pacific 

 and Indian oceans — that is, the depths are between 20 and 30 fathoms. 



303 277 ^ i*23 25 



f.crl.3 (m i TlA 100 ' 



20 



23 



19 



17 



17 



'». 16 



20 



.-'91 24 



-.. 110. 



<_ThundeW„ 2° WJM / 38 2J'., M 

 "„?> Knoll <5,"i5 :'%\ i 2 ?, 2w^ 9 v 

 121 15 m /no,- K r\\ 



J T: lin IT/1 '< ct.a.erl.t. * a ' 



29? 28.1 

 \" L ' 



\ 20;122 



'.'.'33 



145 



45 ^ 07 '' 13 5._ 120 /■*• 

 *? 30 21 27 ,V--.. 119 



JO 30 27 2, „ ffi 



18 



110 



175 

 420 



\ 19 19 



^ ■- 22 21 



.*. r ■■*• 



\ 5 1 22 1 

 \' 13 J 



218 1 28 . 



24"21" " " " "" 252 ° 



"lT 2? 18 '• „ i5 13 is 20 



18 Sik. 15 16 ' 7 15 1« 23 '' 



"° 20 15 H 15 16 16 ' 



17 15 



f 201_5 

 U1320 



11 



17, 



11 



? "l5. 

 13 I8 .l612 X150 

 '5'8lo" 



10; 190 



ROSALIND 



13.' 



13 



11 12 



12 '3 12 12 



!•> n 12 u'-.l - 13100 232 

 10 13 I 2 , ill ,/ 1,38, 



.11 13 



_28_21_ 



80M10 



13 1S 17 17' 20 18.109 

 13 " ' 8 H j, i 6 \ 



-18- 



15 



13 13 18 15 15 

 ■- - 18 , 7 « 15 \ 



S M 20 18 W 15 11 18 ' 



22 17 



25 ■• ' 



23 19 



!_L73__J 



15 crl.. 



32 



17 15 



29 1716 I4 13 



14 



23' 



21 19 16 



32" 

 20'U 13 



i4a " 



10 i 12 

 12 H0 

 12 H 13 12 12 11 



13 ,,-"*•'*£,'■»'■»' 

 12 U 12 U 13 , 

 12 16 12 11 13 



,,, 1 13 ' 3 « » I2*ri"37. 

 .'• 12 ., ..12 n ,,12.1.0 iV.18.23: 

 lOi-i) 



14150 



fflVT 



16 H 



'19 '1 Oi-V " ,2>; 10 ^ . 

 \ I3'",: i, 13i3 13 12 13 -' 12 ^I2' Ripple 



\1.1 W >2 I3 12 12 ',? *"/ 



,.32_0^ .17 i2 l °, 1 7? 275 



- 210 42 '50 SO"' 240 iTT« 



<i>. 



■• 12 io„ ii V ">io V-ia:. 1 ? 5 



VI '-.-'^V^-'f 22 ^^ 

 «Y'11 N 9 .i» <c V' *■ " ''/- W .' - 

 1/13 f-?.* * 5 J 1 -«.':'-9>I2-V°144 

 130.16-.?-.-->.9 7 <5'' a -.v^l3i ° c' M 

 ^ " 106 ^.^v# - 138 ^>Y, 



138 ;iJl010-U%„ "° (*, 



SERRANILLA BANK. 



14 15 11 11 



15 '5 16 2 



Fig. 25.— Chart of Rosalind and Saebanilla banks. From U. S. hydrographic chaet No. 364. 



The possibility of the formation of atoll lagoons by submarine 

 solution was eliminated in the discussion on page 250 of this paper. 

 Atoll rims are formed by constructional processes. That the greater 

 abundance and luxuriance of reef-forming organisms on the periphe- 

 ries of atolls is due mostly, if not solely, to the intolerance of such 

 organisms to sediment, is shown by certain of my experiments. If 

 the colonies are protected from sediment, the growth of corals within 

 a lagoon may exceed that of corals on the outside. 



It is my belief that the coral reefs forming atoll rims are superposed 

 on platforms that antedate the formation of the living reefs, and 

 which have undergone a moderate submergence in Recent geologic 



i Amer. Acad. Arts and Sci., vol. 51, pp. 178-199, 1915- 



