THE M1SSISSIPPIAN PERIOD. 501 



(Richmondville [Berea] sandstone) is significant of the climate as 

 well as of the geography of the time. 



The Kinderhook series. — West of the Cincinnati arch, the con- 

 ditions of sedimentation were varied as shown by the nature of the 

 formations. In the early stages of the period the sediments laid down 

 were sometimes clastic and sometimes calcareous. The lowest series 

 in the states bordering the Mississippi is commomy known as the 

 Kinderhook series/ and is characterized by considerable variations 

 in the character of the rock. The sedimentation seems to have varied 

 not only in different places at the same time, but in the same place 

 at different times. The Kinderhook series is to be looked on as repre- 

 senting the time when the sea was in the early stage of its advance. 



The Osage or Augusta series. — A little later the waters of the Mis- 

 sissippi River region became clearer, and the varied sedimentation 

 just referred to gave place to the deposition of the more nearly pure 

 limestone. This limestone represents the second or Osage stage of 

 the period. The sea in which this limestone was deposited extended 

 far to the westward, probably to New Mexico on the one hand and 

 to Montana on the other, though between the 97th meridian and the 

 Rockies the strata then deposited are generally buried by later for- 

 mations. The likeness of the fossils of the Osage limestone of the Mis- 

 sissippi basin to those of the corresponding formation of Europe are 

 thought to indicate some available route of travel for marine species 

 (especially crinoids) between these widely separated regions. What 

 is now known of the distribution of the strata of this stage seems to 

 point to the conclusion that this route was a northerly one, via Grin- 

 nell Land and Spitzbergen, or possibly via Alaska and Siberia (Fig. 228). 

 Shallow water and the absence of great variations of temperature are 

 probably the only conditions necessary for such migration as the faunas 

 of these widely separated regions imply. The Osage series of the 

 immediate Mississippi basin, known in Iowa and Missouri as the Augusta 

 series, consists of several subdivisions which have local names. 2 

 Locally, geodes abound in the series. 



1 For details concerning the Kinderhook of Missouri, see Weller, Jour. Geol.,Vol. 

 IX, pp. 130-48; and Keyes, Vol. VIII, pp. 313-21; and Bull. Geol. Soc. Am., Vol. 

 XIII, pp. 267-92; for Iowa, see Calvin and Keyes, Vols. Ill and XIII, Iowa Geol. 

 Surv. 



2 See reports of Missouri, Iowa, Illinois, Indiana, etc. 



