292 C. R. KEYES — DEVONIAN INTERVAL IN MISSOURI 



has been particularly notable in the case of northeast Missouri in the 

 area occupied by the original Kinderhook. 



In order of their practical values in the field work in this district, 

 these five methods are similarity of lithologic sequence, lithologic simi- 

 larity, faunal comparison, orotaxis, and homogeny.. 



Recapitulation 



From the foregoing the following conclusions may be briefly stated : 



(1) The sediments of Missouri and the neighboring states, regarded 'as 

 Devonian in age, form a well defined terrane that is delimited in a re- 

 markably clear manner both above and below. 



(2) Over the area now occupied by the Ozark dome the Devonian 

 sediments were deposited much in the same manner as farther north- 

 ward, and not around the borders of an Ozark isle. 



(3) The gap in sedimentation during the Devonian interval must be 

 more largely and widely represented to the west of the present line of 

 outcrops along the western flank of the Ozarks. 



(4) The original Kinderhook formation is not a homogeneous terrane, 

 but is composed of parts of two very distinct systems. 



(5) The median shale of the original Kinderhook is stratigraphically 

 continuous with an undoubted Devonian shale, and the two appear actu- 

 ally to form parts of a single formation, which above the mouth of the 

 Missouri river contains in its middle the Louisiana limestone. 



(6) The so-called Chouteau fauna is a composite fauna, and not the 

 fauna of the typical Chouteau limestone of central Missouri. 



(7) Many of the fossils that have been reported from the Chouteau 

 limestone in central Missouri are now known to be not from this ter- 

 rane, but from an entirely different formation. 



(8) A remarkable plane of unconformity appears to exist at the base 

 of the typical Chouteau limestone, the full significance of which is as 

 yet undetermined. 



(9) Instead of a complete mingling of the different elements of the 

 faunas at the juncture of the Devonian and Carboniferous making up a 

 Devono-Carboniferous zone, so to speak, the biotic changes of the two 

 systems are rather sharply contrasted. 



