712 LOUIS AGASSIZ. 



quarantine, Agassiz was only allowed to land 

 at the Mount, a hill on the western side of the 

 bay, the geology of which he was anxious to 

 examine. He found true erratics — loose peb- 

 bles, granite, gneiss, and granitic sandstone, 

 having no resemblance to any native rock in 

 the vicinity — scattered over the whole sur- 

 face of the hill to its very summit. The hill 

 itself had also the character of the "roches 

 moutonnees " modeled by ice in the northern 

 hemisphere. As these were the most northern 

 erratics and glaciated surfaces reported in the 

 southern hemisphere, the facts there were very 

 interesting to him. 



With dredgings off the Rio de la Plata, and 

 along the coast between that and the Rio Ne- 

 gro, the vessel held on her way to the Gulf 

 of Mathias, a deep, broad bay running some 

 hundred miles inland, and situated a little 

 south of the Rio Negro. Here some neces- 

 sary repairs enforced a pause, of which Agas- 

 siz took advantage for dredging and for study- 

 ing the geology of the cliffs along the north 

 side of the bay. As seen from the vessel, they 

 seemed to be stratified with extraordinary 

 evenness and regularity to within a few feet 

 of the top, the summit being crowned with 

 loose sand. Farther on, they sank to sand 



