134 ANNALS NEW YORK ACADEMY OF SCIENCES 



find conditions similar to those prevailing in the oolitic strata; limestones 

 untouched by iron-bearing solutions, but with overlying and underlying 

 iron-ore seams; lenses from a few inches to many feet in length composed 

 of limestone witli only a slight marginal penetration of the iron, and yet 

 entirely surrounded by iron ore (Plate XIV, fig. 1). In ])laces, fractures 

 in the limestone beds have been penetrated, by iron and the* walls of the 

 breaks lined with ore. In other occurrences, the iron has followed seams 

 or laminations in the limestones and has replaced the limestone along 

 these planes of weakness (Plate XV). 



A generally prevailing condition of apparent replacement in all stages 

 is found in both fossiliferous and oolitic beds, in which both calcite and 

 quartz show corrosion and replacement (see photomicrographs, Plates 

 XVI, XX, XXI). 



Inadequacy of Sedimentation in Open Sea 



The conclusion seems justified that, whereas widespread similarity of 

 conditions should be expected, with unbroken evidence ot the presence of 

 marine iron-bearing solutions in the sedimentary beds (whether of sand- 

 stone, limestone, shale or clay), yet the reverse conditions actually exist, 

 for (1) small lenses of loose sand untouched by iron-bearing solutions 

 are found, which, under the conditions imposed by any sedimentary 

 theory, could not have been free from the iron; (3) two unlike consoli- 

 dations, one without iron, the other surrounding the first and completely 

 charged with iron — a circumstance that would have been impossible 

 under the sedimentary conditions pointed out by the various advocates 

 of marine deposition of iron ores; (3) differently coated oolites in the 

 same immediate locality would hardly seem possible under such a theory ; 

 (4) the penetration of iron into seams, lamination planes, weakened 

 strata, mudcracks and fissures running off from the main ore beds could 

 hardly be explained under theories depending upon a primary origin of 

 the ores. 



Sedimentation in Lagoons 



In regard to a growth witliin inclosed lagoons or basins of shallow 

 water, the field evidence in some yjlaces may bear this out. The writer's 

 observations, however, have seemed to show much active wave erosion and 

 considerable rather violent agitation of the sea-water. This is illustrated 

 by what appear to be two well-formed stacks which could only have been 

 shaped by wave erosion ; one at Clinton, Xew York, and the other at Eed 

 Mountain, Birmingham, Alabama. Further evidence might be suggested, 

 as, for example, the existence of several kinds of varieties of coral which 



