REMARKABLE GEOLOGICAL SECTION. I 73 



the only or most substantial reward for my long and arduous climb to the 

 summit. I had been repaid by the discovery of the most important con- 

 tinuous geological section I had yet seen in Patagonia. At the base were 

 several hundred feet of Cretaceous materials, embracing several distinct 

 horizons. Next followed some fifty feet of basalt, which in places exhib- 

 ited a highly columnar structure. This in turn was overlaid by about 

 one thousand feet of marine Tertiary deposits, rich in fossil remains, while 

 above this came fifteen hundred feet of rock belonging to the Santa Cruz- 

 ian formation, and at the extreme top there were from two to three hun- 

 dred feet of marine beds belonging to the Cape Fairweather formation, 

 already mentioned as first discovered at Cape Fairweather, distant some 

 five hundred miles. 



As I climbed my way up through the rocks belonging to the Santa 

 Cruzian formation, I came frequently upon the bones and teeth of Neso- 

 dons, Typotheres, armored and unarmored edentates and other animals 

 with which I had already become familiar. These were, as a rule, too 

 fragmentary, however, to be of any value, except as determining the 

 horizon of the beds, and, for the most part, they received only a passing 

 glance. As I neared the summit, however, I came upon a place where a 

 softer stratum of clay had weathered away more rapidly than the harder 

 materials of the sandstones above and below. This had resulted in the 

 formation of a level terrace several feet in breadth, on which I could walk 

 comfortably, giving my attention to a survey of the surrounding rocks in 

 quest of fossils, with no danger of losing my footing and tumbling head- 

 long back down the precipitous cliff, as had been the case throughout a 

 considerable portion of the distance through which I had climbed. I con- 

 tinued my walk but a short distance along this terrace when I came upon 

 a splendid skull of Nesodon protruding from the face of the sandstone 

 above me. This, on account of its size, prohibited my canying it away. 

 Continuing a little farther, I ascended to another and more extensive 

 platform. Hardly had I reached the surface of this when I discovered an 

 almost complete skeleton of a fossil bird of about the size of the blue 

 heron, while close at hand lay another fossilized skeleton belonging to 

 Diadiaphorus, an ungulate mammal, and near at hand lay several skulls 

 and parts of skeletons of small carnivorous marsupials. I carefully took 

 up and packed in my collecting bag the bird skeleton, a portion of the 

 skeleton of Diadiaphorus and one or two of the marsupial skulls, and on 



