210 



Tlie only other fossils yet fouud in the shales consist of obscure, 

 flattened casts, probably of some marine plant, together with a 

 number of minute, discoid bodies, sometimes arranged in little 

 chains, but of which I can make nothing. 



Above the shales, just described, is a heavy bed of a not well lami- 

 nated clay-rock, white, mottled with red, in Avhich I have found 

 nothing except some very obscure fucoid-like markings. All these 

 beds have a very slight inclination to the south-eastward. Going 

 northward, the bluflFs gradually increase in elevation, but are proba- 

 bly nowhere more than fifty feet in height. The inclination of the 

 beds of the Erere plain is quite variable, and, over large areas on 

 both sides of the igarape, they are almost perfectly horizontal, often 

 forming open campos of large extent, which are sometimes so ex- 

 ceedingly stony as to appear as if macadamized, the soil not being 

 sufficient to support even a growth of grass. 



The lowest beds of the series, that I have examined, are exposed 

 in the north-western part of the campo at the cachoeirinhas of 

 Paric4* and Cumamirif situated on branches of the igarape de 

 Erere. At the former locality the rock varies from a very hard, 

 dark-colored, silicious shale, to a well bedded, dark gray, compact, 

 cherty rock, breaking with a conchoidal fracture. The strike of 

 these beds, taken along a water-line, is N. 10-15° W., the dip being 

 westward and exceedingly slight. Leaving this locality and going 

 eastward, the surface of the plain rises noticeably for about a mile, 

 the dip being towards the west, continuing with but few elevations 

 to the cachoeirinha do Igarape do Cumamiri, where similar cherty 

 rocks, with the same very slight westward dip, are seen in the bed of 

 the stream, forming, during the dry season, a little cascade, which at 

 the time of my visit was not more than two feet in height. The 

 cherty beds have afforded no fossils, except a few fragments found 

 in the more shaly portions. 



BetAveen the cachoeirinhas, above named, the beds are traversed by 

 two dykes, which crop out, much decomposed on the surface; one 

 forming a low ridge running nearly north-south, while the direc- 

 tion of the other is nearly east-west. On the right bank of the 

 igarape de Erere, and some distance above the trail to Monte- 



* A tree, funiisliiug a seed out of which the Indians make snuff, 

 t This appears to mean Little Milk. 



