IOWA ACADEMY OF SCIENCES. 43 



Near Coburg the Cretaceous appeal's to be quite heavy, but if this forma- 

 tion is found to extend southward and into Missouri where no areas, how- 

 ever limited in extent, have yet beeu found, it would no doubt be quite thin 

 unless in exceptionally rare cases, for towards the southern boundary of 

 Page couBty the Carboniferous rocks are not infrequently found, where 

 exposed, a considerable distance above the drainage line, the ridges are not 

 more elevated above them nor the drift less thick upon the upland. 



Just how far the shoi-e line of the Cretaceous sea extended southward 

 cannot detinitely be figured now, but, considering the position and abun- 

 dance of outliers to the south and southeast along the present border, the 

 direction the glaciers advanced and the readiness with which the friable 

 beds could be broken off and carried away, one can immediately conceive 

 how this shore line and the main deposit have been extensively altered, and 

 how the present southern boundary may be far northward of the southern 

 shore-line of the then probably continuous deposit. 



For the present, however, it seems desirable to call the exposure near 

 Essex at least very near the farthest south any Cretaceous in situ exists in 

 Iowa; realizing at the same time the possibility, if not probability, that such 

 may yet be found southward and in Missoui'i. 



The finding of Cretaceous boulders amongst the drift is by no means 

 uncommon. At the foot of the Missouri bluffs near Henton, in Mills 

 county, a number of irregularly shaped masses of pudding stone were 

 secured. Those were quite similar to the bedded stone in some of the coun- 

 ties further eastward. Just across into Missouri from Blauchard, Iowa, on 

 the bank of the West Tarkio is, in a cut recently made, a fifteen-foot bed of 

 more or less clayey sandstone doubtless Cretaceous in origin but modified 

 on being removed and deposited here by the glacier. It would not seem 

 that this sandbed nor the pudding stone had been carried away any great 

 distance from their place of original deposition but their soui'ces are yet to 

 be traced. 



TOPOGRAPHY OF THE GRANITE AND PORPHYRY REGION OF 

 MISSOURI. 



BY E. H. LONSDALE. 



When speaking of the Arch;van hills of Missouri Pumpelly has likened 

 them unto "an archipelago of islands in the Lower Silurian strata which 

 surrounded them as a whole and separate them from one another." To one 

 who knows this interesting territory with its isolated and grouped knobs 

 hills and mountains of crystalline rocks standing out more or less promi- 

 nently and dotting the broad expanse of more recent sedimentaries, this 

 figure is an exceedingly happy one; one most admirably taken. 



In order to appreciate the picturesqueness of the scenery there presented 

 it becomes requisite that not merely a birds-eye view be taken but also to 



