209 



On tlie left bank of the stream, above the fazenda, begins a very 

 extensive and beautiful grove of miriti palms, which occupies a 

 marshy tract, that seems to be quite dry during several mouths of 

 the year. A little farther on we meet with higher lands on the left 

 bank, and on the same side, between the upper and lower ports of 

 the village of Erere, there is a narrow ridge of sandstone, rising 

 about twenty feet above the general level of the campos, and which 

 runs off eastward, perpendicular to the river. This ridge is very 

 much broken, the sandstone lying in huge masses, overgrown with 

 trees and spiny shrubbery, so that I found it very difficult to exam- 

 ine it, and I could not satisfiictorily determine the direction of the 

 strata. The rock is, for the most part, a very hard sandstone with 

 a clayey cement, but some of the beds are very argillaceous and 

 beautifully striped with brilliant colors. 



"We have now emerged from a sort of pass between the Erere and 

 Monte-Alegre highlands, and have entered a vast, low plain, sur- 

 rounded by hills and high ground on all sides. From north to 

 south this plain probably measures not less than fifteen miles, while 

 its width from east to west must be over ten miles. It lies a little 

 higher than the alluvial plains of the Amazonas, and is drained by 

 the igarape by which we have just ascended. It is composed of 

 nearly horizontal strata of Devonian age, through which the 

 igarape has cut a little valley, now partially filled in with alluvial 

 deposits, lying at a lower level than the plain, the Devonian strata 

 forming low bluffs bordering them. The valley narrows to the 

 northward, and, in the upper part, the igarape flows directly 

 through, and over the Devonian rocks, a clear water stream. 



In a little bluflf by the side of the road leading from the igarape 

 to Erere, and just as one ascends from the alluvial flat, there is an 

 exposure of about fifteen feet in thickness of the Devonian beds. 

 The lower part of the bluff is composed of soft, well-laminated, fine- 

 grained shale, dark gray in color, alternating with white or red 

 layers, and consisting of a fine, more or less sandy silt, with an 

 abundance of little flakes of mica. This locality was discovered in 

 1870 by my assistants, Messrs. T. B. Comstock, Herbert Smith, and 

 Phineas Staunton, who collected from the variegated shales a pretty 

 little Discina, with which are associated two species of Lingula. 



BUL. nUF. SOC. NAT. SCI. (27) JAXCARY. 1874. 



