258 ANNUAL RECORp OF SCIENCE AND INDUSTRY. 



Campbell, and by Major W. J. Twining, the chief astrono- 

 mer of the Survey. He secured seteral thousand insects, and 

 other alcoholic collections, over a thousand skins of mammals 

 and birds, many nests and eggs, an herbarium, and numerous 

 miscellaneous objects. The continuance of the survey next 

 year will probably enable him to extend his observations to 

 the Rocky Mountains, along the same line, and more inter- 

 esting results may be anticipated, owing to the less well- 

 known nature of the remaining portion of the survey. 



EXPLOEATIONS OF PKOFESSOR POWELL. 



The explorations of the valley of the Colorado River of the 

 West have been continued during the jDast year by Professor 

 Powell. 



A topographical party in charge of Professor Thompson 

 remained in the field during the winter of 1872-3, and Pro- 

 fessor Powell returned to it in April. The system of trian- 

 gulation, previously begun to the north of the Grand Caiion 

 of the Colorado, has been extended so as to include all tlie 

 country drained by the Rio Virgen, Kanab, Tapete, Paria, Es- 

 calanti, and Dirty Devil rivers, and the head waters of the 

 Sevier, and an extensive district of country to the east of 

 the Colorado River and to the south of the Grand Caiion. 



Based on this triangulation,an elaborate topographical map 

 has been made of the above-mentioned country. This map 

 presents some curious features, as the region of country delin- 

 eated is unique. Instead of presenting a series of plains, 

 with hills and mountains rising therefrom, it delineates a 

 series of mesas and plateaus, separated by lines of cliffs, and 

 rising one above another in such a manner as to present the 

 appearance of irregular geographical terraces on a vast scale. 

 Through these table-lands are excavated deep water-courses 

 known as caiions, so that sunken, rather than raised features 

 must be represented ; hence it is not so much an orographic 

 map as a chart of profoundly eroded water-ways. < 



While the astronomical and topographical work necessary 

 to the production of this map has been carried on by Pro- 

 fessor Thompson and his assistants, Professor Powell has 

 been engaged in the geological examination of the district, 

 especially in tracing a great system of faults and folds which 

 extend through this country, and a vast number of extinct 



