404 A JOURNEY IN BRAZIL. 



de Janeiro to the top of the Serra do Mar, where, just out- 

 side the pretty town of Petropolis, the river Piabanha may 

 be seen flowing between banks of drift, in which it has ex- 

 cavated its bed ; thence I have traced it along the beautiful 

 macadamized road leading to Juiz de Fora in the province 

 of Minas Geraes, and beyond this to the farther side of the 

 Serra da Babylonia. Through out this whole tract of country 

 the drift may be seen along the roadside, in immediate 

 contact with the native crystalline rock. The fertility of 

 the land, also, is a guide to the presence of drift. Wherever 

 it lies thickest over the surface, there are the most flourish- 

 ing coffee-plantations ; and I believe that a more systematic 

 regard to this fact would have a most beneficial influence 

 upon the agricultural interests of the country. No doubt 

 the fertility arises from the great variety of chemical ele- 

 ments contained in the drift, and the kneading process it 

 has undergone beneath the gigantic ice-plough, a process 

 which makes glacial drift everywhere the most fertile soil. 

 Since my return from the Amazons, my impression as to 

 the general distribution of these phenomena has been con- 

 firmed by the reports of some of my assistants, who have 

 been travelling in other parts of the country. Mr. Fred- 

 erick C. Hartt, accompanied by Mr. Copeland, one of the 

 volunteer aids of the expedition, has been making collections 

 and geological observations in the province of Spiritu Santo, 

 in the valley of the Rio Doce, and afterwards in the valley 

 of the Mucury. He informs me that he has found every- 

 where the same sheet of red, unstratified clay, with pebbles 

 and occasional boulders overlying the rock in place. Mr. 

 Orestes St. John, who, taking the road through the in- 

 terior, has visited, with the same objects in view, the 

 valleys of the Rio San Francisco and the Rio das Velhas, 



