398 



REPORT OF NATIONAL MUSEUM, 1904. 



erratic rocks of North America, Christy showed himself to have been 

 a catastrophist. He believed that there had been two periods of ele- 

 vation of the land in the history of the continent, with an intervening- 

 submergence. The second and last emergence he regarded as having 

 been .rapid and to have given rise to the swift currents which were 

 instrumental in producing the drift. 



In the spring of 184:6, A. Wisiizenus, a " German by birth and an 



American by choice," left St. Louis, Missouri, with the intention of 



making a tour through northern New Mexico and upper California 



for the purpose of examining into the ffeoefraphy and 



Wislizenuss , , i , • - * ,, / - ■£ * 



Explorations in genera] natural history <>t the country. I'ntortu- 



Mexico, 1846. , ,. , • • - ,• , , tt • i 



nately tor his intentions, war between the United 

 States and Mexico broke out while he was within the jurisdiction of 

 the Mexican Government, and he was compelled to remain within the 

 State of Chihuahua for a period of six months or until the arrival of 



the American troops, when he accepted a 

 position in the medical department and re- 

 turned with it by way of Monterey to the 

 States. 



His opportunities for observation were, 

 naturally, much less than was at first antici- 

 pated, and his geological report, amounting 

 to but five pages, was published as a part of 

 Senate Miscellaneous Document No. 26 of 

 the thirtieth Congress, first session. In this 

 report he noted that the bluffs on the Arkan- 

 sas some 341 miles from Independence were 

 of a grayish conglomerate limestone, con- 

 taining fossils which tk seemed to belong to 

 the Cretaceous formation." Near Las Ve- 

 gas he found a dark blue limestone with casts of Jnoceramus, which 

 were also relegated to the Cretaceous series. Near El Paso he noted 

 the presence of a limestone containing the fossil coral Calamopora and 

 the bivalve shell of the genus Pierinea, which, as a consequence, he 

 considered as belonging to the Silurian formation. The presence of 

 numerous eruptive rocks were noted and an outline map published, 

 in which the lithological nature of the rocks was indicated. The map, 

 it should be noted, comprised the area lying between the Arkansas 

 and the Rio Grande rivers, but extended south and west of the latter 

 as far as Montere} r and Chihuahua. 



The fine silt-like character of the superficial deposits 

 fhe "oessMTb ° n of the Mississippi Valley had frequently been noted by 

 the various geologists who passed over the region, but 

 it remained for Amos Binney, tin 1 conchologist, to give the first rea- 

 sonably satisfactory account of its probable origin. At a meeting of 



Fig. 10. — Frederick Adolphus 

 Wisiizenus. 



