Douglass : A Geological Reconnaissance. 245 



crops are the exception rather than the rule. The road does not 

 follow the stream, as the valley closes in and is rugged and rocky. 

 After travelling for some distance the hills became relatively less ele- 

 vated and the intervening flats or depressions more extensive. In 

 some of these depressions there are beds of temporary lakes, which 

 doubtless furnish examples of combined aqueous and aeolian deposits. 

 During heavy rains or the melting of snows, the waters which accumu- 

 late in these depressions must take considerable fine sediment with them. 

 The dust, which in dry weather is blown from the surrounding semi- 

 arid region, is caught by the water and remains there. One of these 

 lake-bottoms, which at the time of the previous journey was covered 

 with water, was now dry, hard, and sun-cracked, and I drove across 

 it without danger. Ascending a hill or ridge from the level lake-bed, 

 I descended to the broad valley of a little stream which flows through 

 sage-brush flats and rather poor pasture lands. It is a feeble stream 

 which is fed in dry weather by seeping springs. Its little cut-banks 

 show recent superficial deposits probably of hillside- or sheet- wash and 

 aeolian dust. 



East of the road from Big Timber to Melville and south of Sweet- 

 grass Creek, which here flows eastward, some bluffs were examined. 

 The sandstones and shales are well exposed, the latter containing 

 some bones of a reptile (^Champsosauriis), and the former leaves of 

 plants. The beds are probably Fort Union. From this place to and 

 beyond Melville the country is more level, and the greater portion of 

 it is covered with deposits made by Sweetgrass Creek, the valley of 

 which here broadens into a quite extensive plain. North of Melville 

 are large meadows, and beyond these a butte (Melville Butte) which 

 extends northward nearly to Fish Creek. This butte lies east of the 

 much larger, mountain-like Porcupine Butte ; but the latter sinks into 

 comparative insignificance on account of its nearness to the high, 

 sharp, abrupt peaks of the Crazy Mountains. At the lowest exposure 

 in the south lobe of the base of Melville Butte, are alternating sand- 

 stones and dark shales. The heavier layers of sandstone, by resisting 

 atmospheric influences, have preserved this foot-hill of the butte. 

 Here fresh-water shells {Untos^ and fossil leaves were found. An- 

 other higher lobe of the butte is topped by flaky shales in which there 

 are a few bands of sandstone. In these shales were found bones of 

 reptiles, among which were Champsosaurus. Above this the sandy 

 bands in the shale are more numerous. In one band fossil leaves 



