146 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
along the line of the road to ascertain the depth of the mud down to 
the rock floor. These soundings were taken with steel rods, and the 
mud was so soft that two or three of the rods were lost by slipping from 
the hands of the men and disappearing very much as if they had fallen 
into water. The original profile of the railway, together with rock cuts 
and soundings across these mangues, was kindly furnished me by Mr. 
Agnew. They are copied here, beginning with the upper left hand at 
kilometre 16 from Cabedello. 
It will be seen that the mangrove swamp here fills gullies that were 
cut originally in the hard limestone. The outlines show them to have 
the form common to stream channels, and as such channels could only 
be cut when the place was above water level, we are obliged to assume 
that the land at this place formerly stood enough higher to allow water 
to flow freely down these gullies. The greatest depth of the mud along 
the profiles is 11.70 metres, which, added to the depth of water in the 
mangue above the mud, gives a total depth of at least 12 metres. In 
order to restore the conditions under which this deepest channel was 
cut, we must assume an elevation of the land of at least twelve metres. 
But inasmuch as the railway runs across only the upper or shallower 
ends of these swamps near the Parahyba hills, it is fair to assume that 
the main channel of the Parahyba is considerably deeper. Their prox- 
imity to the hills likewise precludes the possibility of the channels 
having been cut by tidal scour. 
Additional views of depression. — Shaler expresses the opinion, prob- 
ably based upon such maps of South America as are available, that the 
region about the mouth of the Amazon “has recently been lowered to a 
considerable depth.” 1 
Dr. James Geikie says: “The general trend of the coast-line of South 
America . . . from Pernambuco to the mouth of the river Plate, coin- 
cides with the direction of the continental plateau, and may be said, 
therefore, to have been determined by crustal movements.”? Не thinks 
the region about Rio has been depressed. 
Although Hartt expressed a belief in a recent elevation of the coast, 
he algo refers to evidence of a recent depression. This evidence consists 
of recent cemented sands covering “drift” clays “down nearly to low 
tide. This fact seems to prove satisfactorily that formerly the land 
stood at a higher level even than now.” * 
1 М. S. Shaler. Evidences ав to change of sea-level. Bull. Geol. Soc. Amer., 
1895, УТ., p. 162. 
2 James Geikie. Earth sculpture. New York, 1899, р. 332. 
3 Geology and physical geography of Brazil, р. 572. 
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