372 The Amei'ican Geologist. December, isoi 
Lower Cretaceous. WeaUlen or Middle Neocomian calcareous 
strata in the same county, give place to oolitic brown ironstone 
which is described as highly fossiliferous as well as calcareous. 
The same strata are overlain conformably by the Lower Green- 
sand series of arenaceous shales, with which is imbedded lime- 
stone passing into ironstone.* 
^A'/. liculaciiiHiit <if Jjio.ssic h'liicstonc Jjii.riiiiliii nj nml Tjurraine. 
The oolitic limonitesof Luxemburg and Lorraine, ecjuivalent with 
theores of the Cleveland district of Yorkshire, and of the .same gen- 
eral character, bear likewise evidence of replacement of limestone. 
Highly calcareous, as practically shown l)y their self-fluxing prop- 
iM'ty. they contain remnants or nuclei of unaltered limestone, as 
well as numerous molluscus shells transformed into limonite. f 
XII. JicpJdcciiiciit (if McsozDie liiiiestoncs, antral France. 
Some very striking exhibitions of the class of phenomena 
which it is here sought to illustrate, are afforded on a large scale by 
well known deposits of limonite and hematite within the develop- 
ment of Jurassic and Cretaceous limestones in the ancient proA'- 
ince of Berry, now included in the Department of the Cher, in 
central France. I refer to occurrences recently studied by M. 
de Grossouvre. + A graphic description l)y this engineer leaves 
scarcely room for doubt of the origin of these dej)osits by in- 
<lirect replacement. In the elaborate memoir now referred to, 
no attempt is made to trace the process of epigenesis beyond the 
action of solvent chalybic waters in excavation of limestone, and 
in deposition of ferric hydrate in its place. So far from being 
the simplest statement of the process of indirect replacement, 
this explanation is upon the assumption of chemical erosion of 
the limestone as a distinct act antecedent to precipitation of 
ferric hj^drate, or, however insupposable, of anhj'drous ferrous 
carbonate. Hence, as imagined, the formation of caves, cavi- 
ties, basins, etc.. in limestone, followed by the filling of such 
receptacles with products of chemical precipitation. The same 
i-easoning has often l>een applied to similar occurrences in this 
country and elsewhere. Reasons in general against such an 
assumption have alread}' been given. The theory of molecular 
♦Bauerman, Met. of iron, 187^, 9L 
tM. A. Ilabets, Jour. Iron & St. Inst. 1873, 285. 
JAnn. des Mines x, 1886, 311-416. 
