1 66 PATAGONIAN EXPEDITIONS I NARRATIVE. 



for our horses. Here, as subsequently became our custom, now that we 

 were travelling through an unknown country, we remained for a number 

 of days, while I examined the geology and geography of the surrounding 

 region and Mr. Colburn employed himself with the birds and mammals 

 of the more immediate vicinity. 



During our journey across the table-land, before arriving at the canon, I 

 had detected in the distance to the eastward what I thought to be extensive 

 exposures of sedimentary rocks. The following morning I proceeded on 

 horseback to determine the extent and nature of the supposed sediments. 

 Following along the crest of the bluff above the main valley, it was seen 

 to have an average width of about ten miles. Through this valley there 

 ran a small stream, Spring Creek, at first with a considerable current. 

 As I descended the valley, however, the stream became successively more 

 sluggish, until it finally terminated in a small lake with a diameter of 

 perhaps a mile. An examination of the shores of this lake showed that 

 it was subject to periodical overflows when, by melting snows or heavy 

 rains, the volume of water became so much increased that it overflowed 

 the lower border of the lake, where a rather deep channel had been cut 

 through the upper part of the retaining embankment. Below this lake 

 the valley extended for several miles, with numerous springs along its 

 northern border, until ending in a lake some three or four miles in diame- 

 ter, almost entirely surrounded by a series of rugged bluffs, consisting of 

 igneous materials, barren brown sandstones and dull red porphyries, the 

 latter not unlike in general appearance those already mentioned as occur- 

 ring at Port Desire on the Atlantic coast. A careful and continued search 

 among the sandstones was unrewarded by the discovery of any fossils, 

 save a few uncharacteristic plant impressions. 



The lake was, for the most part, quite shallow, but in its waters there 

 grew a profusion of aquatic plants, while the dead shells of a species 

 each of gastropod and bivalve Mollusca were literally piled in diminu- 

 tive winrows along the beach, testifying to the abundance of animal life 

 within its waters. The plant and animal life so abundant in the lake 

 made of it a favorite resort and feeding-ground for the various water fowl 

 indigenous to this region, and at the time of this my first visit in early 

 March, 1898, it was literally alive with these birds. Duck and plover 

 were there by thousands, while the American grebe and the flamingo were 

 not wanting. But the most striking feature of the avian fauna was the 



