40 



DESCRIPTIONS 



of rounded pebbles, red, grey, or rust-colour, as under the 

 superincumbent rocks at Mount Holyoke, the Palisades, on 

 the Hudson river, &c. 



Localities. Its bassetting edges lie directly on the millstone 

 grit. Both divisions, and all the varieties, but the conglome- 

 rate, may be seen at Genesee Falls and in the banks of the 

 Niagara river ; also at Oak Orchard Creek. The conglome- 

 rate and sandy varieties are seen on Connecticut river, and at 

 New-Haven under the basalt ; also on the Hudson above 

 New- York under the pallisadoes. Salt springs are found in 

 it every where west of Rome ; but none have been discovered 

 under the basalt of this country. 



Subordi- 1^' FERRIFEROUS RocK, is a soft, slaty, argillaceous, or 

 Date series. ^ hard, sandy, silicious, rock, embracing red argillaceous iron 

 ore. Subdivisions. Slati/, consists of green, or bluish- 

 green, smooth soft slate, generally immediately under the 

 layer of red argillaceous iron ore. Sandi/, consists of a grey, 

 or rusty-grey, aggregate of quartzose sandrock, in compact 

 blocks or layers, overlaying or embracing red argillaceous 

 Ferriferous, iron ore. Variety. Conglomerate, consists of rounded peb- 

 bles, cemented together by carbonate or oxyde of iron, or ad- 

 hering without cement. 



Localities. It reposes on the saliferous rock every where 

 west of Little Falls. The sandy division lies over the slate, 

 and a layer of red argillaceous iron ore, about a foot or a foot 

 and a half in thickness, lies between them ; or alternates with 

 the layers of one or both. The slaty division is generally 

 green or blue, and very soft. The sandy division is harsh, 

 coarse, and often conglomerate at the top. The softest varie- 

 ty of the iron ore is called reddle, and is used as a paint. 



15. Lias, is an argillaceous limestone, with an admixture 

 of magnesia, iron, and finely pulverized quartz ; forming a 

 compound of a homogeneous aspect. Subdivisions, ^rgilla- 

 eeousj when it approaches the character of clay slate. Cal- 



