[Reports volI-XIII] . stone is exposed in a broadbelt around the Ozark uplift. It reaches a thickness of over150 feet in places. Lithologically it is very much like the otherlimestones of the series, being composed chiefly of buff mag-nesian beds, usually fine-grained and compact in texture. Oftenthere are intercalated layers of chert, sandstone or earthy lime-stone. Broadhead has regarded this formation equivalent tothe Oalciferous sandrock of New York ; but the fossil remainsthus far found are far too meager to enable its fauna to be madeout with any degree of certainty. The character of the
[Reports volI-XIII] . stone is exposed in a broadbelt around the Ozark uplift. It reaches a thickness of over150 feet in places. Lithologically it is very much like the otherlimestones of the series, being composed chiefly of buff mag-nesian beds, usually fine-grained and compact in texture. Oftenthere are intercalated layers of chert, sandstone or earthy lime-stone. Broadhead has regarded this formation equivalent tothe Oalciferous sandrock of New York ; but the fossil remainsthus far found are far too meager to enable its fauna to be madeout with any degree of certainty. The character of the rockis well shown in the gorge of the Missouri, from Jefferson Citymany miles down the stream. (Plate i.) In lithological characters the First or Saccharoidal sand-stone is a white, fine-grained, homogeneous rock, very pure, fri-able, but withstanding the weathering influences in a remarkablemanner. Locally it has a small percentage of iron, turning thestone to a brownish or reddish color. (Plate ii.) oao _io Ul a 3O. o u. o< Q. UJ Z o I- coa z< CO -I< QO <Ioo< CO BASAL SANDSTONES. 35 Worthen regarded this sandstone as exposed on the Mis-sissippi river at Cap-au-Gris, above the mouth of the Missouri,the representative of the Saint Peter sandstone of northeast-ern Iowa and the adjoining parts of Illinois, Wisconsin andMinnesota; but the correctness of this correlation is verydoubtful. Until quite recently, little additional information has sup-plemented Swallows observations of forty years ago. Eecentinvestigations in the field go to show that much confusion hasexisted concerning the different limestones and sandstones,and that, for instance, the second sandstone of one localityis not the second sandstone of other places. Furthermore,there appear to be good grounds for believing that there is adecided physical break between the saccharoidal sandstoneand the second Magnesian limestone, though thus far theline of unconformity has been noticed at but few points.
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