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SCIENCE 



[Vol. LVI, No. U41 



cently with Professor W. G. Fearnsides, of 

 Sheffield, England, that the association was 

 familiar to him and had been described by him 

 in print. He mentioned a number of other 

 occurrences and gave in addition several refer- 

 ences to British publications which discuss the 

 relation of phosphate beds to stratigraphic 

 breaks. As all this evidence serves to establish 

 the principle on a solid basis it seems worth 

 while to bring it to the attention of American 

 stratigraphers. 



The de^Dosit of basal glauconite described by 

 Fearnsides* and Anderson^ is at the boundary 

 between the Cambrian and Ordovician of 

 Sweden and is very extensive. Another deposit 

 of wide extent, described by Hayes," is at the 

 boundary between the black Chattanooga shale 

 and the overlying carboniferous in Tennessee. 

 Both of these are associated with phosphate. 

 The association of glauconite and phosphate is, 

 in fact, so generally referred to in the literature 

 relating to either of them, especially in that 

 relating to nodular phosphate, that it may be 

 regarded as established. Anderson" not only 

 recognized it but interpreted the relative abun- 

 dance of one or the other. He formulated the 

 principle that in deposits of the two constitu- 

 ents iDhosphate predominates in the littoral 

 facies and glauconite in the offshore shallow- 

 water facies (essentially the continental shelf). 

 If this practical equivalence in mode of occur- 

 rence of glauconite and phosphate is recog- 

 nized, then the papers referred to in this note, 

 although most of them deal with phosphate de- 

 posits, serve to establish beyond reasonable 

 doubt the association of certain types of glau- 

 conite as well as of phosphate deposits with 



1 rearnsides, Wm. G. : " The Lower Ordovician 

 Eoeks of Scandinavia," etc., Geol. Mag., n. s., 

 Dec. 5, 4, pp. 257-267, 295-304 (especially pp. 

 264-267), 1907. 



5 Anderson, J. G. : uber Camibrische und Silu- 

 riselie phosphoritfiihrende gesteine axis Scliweden, 

 Bull. Geol. Inst. Univ. Upsala, 2, pp. 133-236 

 (especially pp. 178-200, 220-229), 1895. 



« Hayes, C. W. : ' ' The Tennessee Phosphates, ' ' 

 Sixteenth Ann. Sept., U. S. Geol. Survey, pt. 4, 

 pp. 611-612, 1895; Seventeenth Ann. Sept., U. S. 

 Geol. Survey, pt. 2, p. 523, 1896. 



7 Anderson, J. G. : loc. cit., p. 221. 



breaks in a stratigraphic succession. As early 

 as 1874 Tawney' stated that the fossils in a 

 phosphate bed represent a long time range, 

 indicating a dearth of sedimentation. The de- 

 velopment of the conception with various mod- 

 ifications may be followed in the references 

 given. In a very recent paper Vaughan^ points 

 out the possible bearing of a glauconite bed in 

 solving the problem of the position and char- 

 acter of the Mesozoic-Cenozoic boundary in 

 New Zealand. 



Two conclusions seem to have impressed 

 themselves on most students of these basal de- 

 posits of phosphate and glauconite : One is that 

 the surfaces on which they occur had not 

 emerged, the other that they represent a long- 

 time interval. 



The reasons for supposing that there has 

 been no emergence are not always very clearly 

 formulated. The principal ones seem to be : 

 (1) The usual absence of any recognizable 

 erosion surfaces underlying the deposits; (2) 

 The absence of an underlying weathering sur- 

 face; (3) The absence of fragments of the 

 underlying bed; (4) Lack of evidence of trans- 

 portation of constituents of the beds; (5) The 

 fact that similar modern deposits form under 

 purely submarine conditions. 



There seems to be room for many fallacies in 

 these assumptions, and at best the demonstra- 

 tion of the fact they are called upon to prove — • 

 that during the interval between the formation 

 of the underlying and overlying bed there was 

 no emergence — does not appear very essential. 

 A long period during which the sea bottom 

 was at or near marine base-level seems to be 

 implied in any case, and that, so far as I can 

 see, implies also an approximation to subaerial 

 base-level of the adjacent land. Slight oscilla- 

 tions of base-level may safely be assumed and 

 are indicated by some of the evidence. Whether 

 these fluctuations have at times brought part of 



s Tawney, E. B. : "Notes on the Lias in the 

 Neighborhood of Kadstock, " Proc. Bristol Nat. 

 Soc, u. s., 1, p. 174, 1874. 



9 Vaughan, T. Wayland : ' ' Correlation of the 

 later Mesozoio and Cenozoic Formations of New 

 Zealand, ' ' Proc. First Pan-Pacific Scientific Con- 

 ference, Pt. 3, Bemice P. Bishop Special Pub- 

 lication, pp. 734-737, Honolulu, 1921. 



