244 ANNUAL OF SCIENTIFIC DISCOVERY. 



sand miles in length, and from 500 to 700 miles in width. It is 

 contrary to all our knowledge of geological deposits to suppose 

 that an ocean basin of this size, which must have been submerged 

 during an immensely long period in order to accumulate forma- 

 tions of such a thickness, should not contain numerous remains of 

 the animals formerly inhabiting it. The only fossil remains of any 

 kind truly belonging to it, which I have found in the formation, 

 are leaves taken from the lower clays on the banks of the Soli- 

 moes at Tonantins; and these show a vegetation similar in 

 general character to that which prevails there to-day. Evidently, 

 then, this basin was a fresh-water basin ; these deposits are fresh- 

 water deposits. But as the Valley of the Amazons exists to-da}% 

 it is widely open to the ocean in the east, with a gentle slope from 

 the Andes to the Atlantic, determining a powerful seaward cur- 

 rent. When these vast accumulations took place the basin must 

 have been closed ; otherwise the loose materials would constantly 

 have been carried clown to the ocean. It is my belief that all 

 these deposits belong to the ice-period in its earlier or later phases, 

 and to this cosmic winter, which, judging from all the phenomena 

 connected with it, may have lasted for thousands of centuries, we 

 must look for the key to the geological history of the Amazonian 

 Valle} T ." . . . " Is it so improbable that in this epoch of 

 universal cold the Valley of the Amazons also had its glacier 

 poured down into it from the accumulations of snow in the Cor- 

 dilleras, and swollen laterally by the tributary glaciers descend- 

 ing from the table-lands of Guiana and Brazil? The movement 

 of this immense glacier must have been eastward ; determined as 

 well by the vast reservoirs of snow in the Andes as by the direc- 

 tion of the valley itself. It must have ploughed the valley bot- 

 tom over and over again, grinding all the materials beneath it 

 into a fine powder, or reducing them to small pebbles, and it must 

 have accumulated at its lower end a moraine of proportions as 

 gigantic as its own ; thus building a colossal sea-wall across the 

 mouth of the valley. I shall be asked at once whether I have 

 found here also the glacial inscriptions, the furrows, strife, and 

 polished surfaces so characteristic of the ground over which 

 glaciers have travelled. I answer, not a trace of them ; for the 

 simple reason that there is not a natural rock surface to be found 

 throughout the whole Amazonian valley. The rocks themselves 

 are of so friable a nature, and the decomposition caused by the 

 warm torrential rains and by exposure to the burning sun of the 

 tropics so great and unceasing, that it is hopeless to look ten- 

 marks which in colder climates and on harder substances are pre- 

 served through ages unchanged. With the exception of the 

 rounded surfaces, so well known in Switzerland as the roclies 

 moutonnies, which may be seen in many localities, and the 

 boulders of Erere, the direct traces of glacial action as seen in 

 other countries are wanting in Brazil. I am, indeed, quite willing 

 to admit that, from the nature of the circumstances, I have not 

 here that positive evidence which has guided me in my previous 

 glacial investigations. My conviction in this instance is founded, 

 lirst, on the materials in the Amazonian valley which correspond 



