Professor (Jh. Fred, Hartt, 3f. A. — Simonds. 79 
"ing on the late rise of the Brazilian coast, a rise which ex- 
"tended itself into the interior. Before this rise the land stood 
. "much lower than at present; the island of Marajo did not 
"exist, and the Araazonas formed an estuary opening widely 
"to the sea. Not only were the lower plains of Para flooded, 
"but immense tracts of the province of Amazonas were cov- 
"ered with water. How far this salt water penetrated I do 
"not know, but the shells of Pebas show that at one time its 
"influence may have extended far up toward the Andes. At 
"the time of the growth of the Santarem shells the water may 
"have been brackish. With the gradual rise of the continent, 
"not of the Andes alone, the fresh waters drove down the salt, 
"the river bed with its numerous side channels was hollowed 
"out of the emerging bottom, the sea began to attack and cut 
"awa}!- the coast lands, and the present estuary condition of 
"the mouths of the great river was brought about." 
He also showed that the so-called "erratics" at Erere, where 
he spent a month, "going over the ground on foot in every 
direction, and in the most detailed way," to have been derived 
from a large mass of trap that had "given rise to a great num- 
ber of boulders of decomposition which lie f>n the surface, or 
are buried in decomposed rock. They have often been carried 
down the beds of torrents, but they are nowhere erratics." 
Again, in a paper "On the Tertiary Basin of the Maraiion," 
published in the Amerivati Journal of Science for July, 1872, 
he expressed his disbelief in the glacial origin of the Amazon- 
ian valley. 
Knowing Hartt's great appreciation of Agassiz, and the 
warm personal friendship that existed between them, I doubt 
not that he felt keenly the necessity of differing so strongly 
from the views of his eminent teacher. To follow science is 
to search for truth. To correct error is essential to progress. 
In this spirit Hartt felt it to be his duty to publish his obser- 
vations to the world. 
In the American Naturalist for May, 1871, vol. v, p. 139, he 
published a paper on "Brazilian Rock Inscriptions," with nine 
full page illustrations, in which he reproduced some of the so- 
called hieroglyphics of the Rio Tocantins, near the lower 
falls, and of the Serra of Erere, on the north side of the Am- 
azon valley, near Monte Alegre, together with some figures 
