360 ^rans. Acad. Sci. of St. Louis. 



The basal member of the section is the Hudson shale. In 

 the neighborhood it attains its full thickness of about 70 feet. 

 It rests on a heavy magnesian limestone carrying character- 

 istic Trenton fossils. 



The next two higher members, Nos. 2 and 3, are provision- 

 ally referred to the Niagara. The oolite appears to be a 

 somewhat local phase. The organic remains contained are 

 rather abundant. The formation appears to be represented 

 elsewhere in the vicinity by fossiliferous limestones which are 

 not oolitic. The buff massive layer is very thin at Louisiana, 

 being only four feet in thickness in the river bluff in front of 

 the town. Two miles southward, at the mouth of Buffalo 

 creek, it increases to 9 feet, and farther southward on both 

 sides of the Mississippi river, and southwestward towards 

 Bowling Green, it attains a measurement of 25 to 30 feet in a 

 distance of 15 to 20 miles. It is almost destitute of fossils. 



The succeeding two, Nos. 4 and 5, belong to the Devonian. 

 The lower black shale contains a characteristic fish fauna. 

 Numbers 6 to 9 form the Louisiana division of the " Kinder- 

 hook." It is the Lithographic limestone of the older State 

 reports. The Hannibal shales, Nos. 10 and 11, contain com- 

 paratively few fossils, but farther north at Burlington, where 

 the beds have always been regarded as non-fossiliferous, an 

 extensive fauna has been of late disclosed, the general facies 

 of which is very decidedly Devonian.* 



The thin, soft, earthy limestone (No. 12), which is nine feet 

 in thickness at Louisiana, is believed to be the attenuated por- 

 tion of the Chouteau limestone, though it is closely associated 

 with the lower beds of the Burlington. Towards the south- 

 west the Chouteau limestone, before leaving Pike County, has 

 a thickness of thirty feet, and still farther in the same direc- 

 tion in central Missouri the thickness increases to over one 

 hundred feet. The lower Burlington limestone is separated 

 upon lithological and faunal grounds, into five zones; and the 

 upper Burlington, as represented in this locality, into three 

 zones. 



* Iowa Geol. Sur., vol. m. p. 80, 1893. 



