;>'^ IOWA ACADEMY OF SCIKNCKS. 



ruder the drift in the Missouri X'alley urc Liieuslriiie cl;iy» 

 and sand, w hicli, further west lie direetly beneath the la'ss, 

 .strongly sui;\i;-estini;- the eonehision tliat r^aice Missouri ma}' 

 hav(^ been th(^ direct successor of the line of i>-rand Tertiary 

 lakes, so ably outlined by Kino- ( Kxpl. 4()th Paral., aoI. 1, 

 i). 4:>.S). 



Fourth. Lake ( 'iieyenne occupied the phiijisfroui Texas to 

 Ahinitoba and eastwaril well toward the Mississippi diirinu- 

 the Pliocene. 



Fifth. Sioux Lake in the Miocene covered th(? western 

 portion of the (xreat Phiius. 



Sixth. In tlie Eoccuk', the surface of the phiins was dry^ 

 ])ut probal)ly not so further north. If not, then this Eocene 

 hike or l)ay would lill t!ie gap and connect this royal line of 

 hdves Avith the ocean. Possil)ly Lake Missouri may have- 

 done so unich later with the Gulf of Mexico. 



ON THE FOLDING OF CARBONIFEROUS STRATA 

 IN SOUTHWESTERN IOWA. 



\\\ PROF. J. E. TOD!). 



{Alts/ract.i 



Most who examined the rocks alono- the Missouri River in 

 the reo-ion vnider consideration liave been constrained to re- 

 cord sonje foldiuii-. but such statements have l)een ration- 

 indefinite and have hardly (>\pressed sufHciently the al)ru])t- 

 ness of the folds. 



Before notin,i;- the evidence of foldin,u's it will be well for 

 us to briefly notice the character of the strata folded. They 

 consist of a mixture of limestone, clays, marlites, slates and 

 sandstone. The chanii'e from one to anotluu- is usually' 

 abrupt and fretiuent. Meek concluded that the nature <»f a 

 stratum chana-ed so much horizontally tliat litholoii'ical char- 

 acters were of little im[)ortance in delerminini>- (Niuivalence 



