86 



DR. A. HOLMES ON THE PRE-CAMBBIAN [vol. lxxiv, 



The Buckingham Series belongs to the Laurentian of Logan, 

 and hence we have an approximate correlation between this great 

 formation and that of the Mozambique gneissose granites, for the 

 two ratios are of the same order. 1 I do not wish to insist too far 



Table XL 

 Data for the Correlation op Pre-Cambrian Rocks. 



Age. 



Mineral. 



Locality. \ Pb %. 



U%. ! Pb/U. 



Analyst. 



? 



Uraninite 



Morogoro, G. E. Africa ... 6*98* 

 ... 6-88 



74-54 0-094 



74-72 ; 092 



Marckwald. 1 



55 



s 



n 



< 



Ph 



Hi 



s 



Broggerite 



Moss, Norway 



8'49f 



8-61 



9-0 



8-8 



8-8 



8-0 



9-3 



8-4 



7-8 



2'2 



018 

 036 



9-4 



9-8 



10-2 



10-14 



8-4 



8-92 

 0014 



67-0 0-13 

 67-4 \ 0-13 

 76-1 0-12 

 67-8 0-13 

 65-2 0-14 

 57-0 0-14 

 65-8 0-14 

 66-0 0-13 

 68-4 0-12 

 15-0 , 0-15 



1-06 0-17 

 2-41 0-15 



56-25 i 0-17 

 56-0 j 0-18 

 612 0-17 



60-0 017 



67-6+ 0-12 > p 

 0-13 j" 

 64-3 0-14 



0-097 > 0-14 

 0-171 i 0-15 

 0-193 0-17 



Hofmann.- 



55 



Lorenzen. 3 

 Hillebrand. 4 



55 

 55 

 55 



55 



Bloomstrand 5 



55 



Holmes. 



55 



Lindstrom. 6 

 Hillebrand. 4 



55 

 55 



Griper." 

 Holmes. 



55 

 55 

 55 



Uraninite 



j, ...... 



Annerodite . . . 



Fergusonite ... 

 Gadolinite 



Uraninite 



Huggenaskilen, Norway. . . 



55 55 



Skraatorp, „ 



Elvestad, „ 



55 55 



Annerod, „ 



55 55 

 55 55 



Ytterby, Sweden 



Arendal, Norway § 





55 



Biotite 







Villeneuve, Canada 



Singar, Gaya, India 



Ligonia R., Mozambique. . 



Zircon 



Monapo River „ ... 0'026 

 Nrassi River „ ... 0"032 





" 







5 « 5 



£ « s 

 J** 



O 



Zircon 



Mozambique 



054 

 0-034 



0-257 0-21 

 0-143 024 



Holmes. 



55 



Sebastopol, Canada 



* Atomic Weigbt = 206-04, Honigschmid & St. Horovitz, 1915. 



f „ „ =206-06, 



X Stated as ' oxide of uranium ' = 79*55. 



§ See footnote 4 on p. 88. 



1 Centralblatt fur Min. u. Geol. 1906, p. 761. 



2 Ber. d. Deutsch. Chem. Gesellsch. vol. xxxiv (1901) p. 914. 



3 Nyt Mag. vol. xxviii (1884) p. 249. 



4 U.S. Geol. Surv. Bull. 220 (1903) p. 114. 



; > Journ. Prakt. Chem. vol. xix (1884) p. 191. 



6 Geol. Foren. i Stockholm® Forh. vol. Ivii (1884) p. 69. 



" Mem. Geol. Surv. India, vol. xxxiv (1902) p. 31. 



1 R. J. Strutt, Proc. Roy. Soc. vol. lxxxiii (1909) p. 300, found 0-0092 per 

 cent, of thorium in the zircons from Sebastopol investigated by him, an amount 

 which is small compared with, the uranium present ; consequently, if this is a 

 general characteristic, any error in the lead-ratio is more likely to be ex- 

 perimental than due to the presence of lead associated with thorium. 



