a. With angular fragments.

Trap tuff, mentioned among the overlying rocks: local.

b. With rounded and angular fragments both. The materials are transported-but this is confined to the vicinity of trap rocks-and often of partial occurrence. May be either primary or secondary.

Similar Conglomerates may occur, consisting of the fragments of mica schist.

Second Division.

Consisting of two rocks or substances, united similarly to the varieties of the former division.

A. Serpentine and limestone; or calcareous spar local. It generally occurs between limestone and serpentine-and is necessarily primary -it includes the verde antique.

B. Fragment, of argillite with limestone. a. Argillite imbedded in limestone,

b. A confused mass of fragments of both. c. Fragments of limestone imbedded in argillite.

These are primary-and some of them valuable. C. Fragments of limestone imbedded in mica schist local.

D. Fragments of granite with mica schist or gneiss local.

:

a. The fragments of granite imbedded.

b. Confused mass of fragments of granite, and of mica schist, or gneiss.

E. Granite uniting fragments of the same rocks and offering similar modifications.

Where mica, schist or gneiss approximates to granite the latter often contains so many fragments of those rocks as to seem conglomerate.

F. Quartz imbedded in limestone : local.
a. In angular fragments.

b. In rounded pebbles.

These are both primary and secondary. G. Trap imbedded in limestone, and in the accompanying shale: local.

The trap is usually in rounded nodules-and apparently weathered: occurs in secondary limestone. H. An aggregate of fraginents of argillite and chlorite schist: local.

This occurs where the two rocks accompany each other, and is local.

I. Sandstone with quartz.

a, The quartz in angular fragments.

b. The quartz in rounded nodules, or united

with angular fragments.

H. Sandstone and lime united.

stone.

a. Fragments of sandstone imbedded in lime

stone.

b. Fragments of limestone imbedded in sand

c. An aggregate of the fragments of both. These are general and belong to the secondary sandstones-mostly to the lowest.

They are mentioned under the heads of the different rocks to which they belong.

L. Sandstone and argillite, or shale, united: general. The sandstone usually forms the base: is enumerated under that head.

Third Division.

Consisting of three or more rocks, o substances united.

These are the most common: they consist of fragments, rounded or angular, or both, united by means of clay, sand, and gravel, derived from the same substances.

A Fragments of quartz, and of a greater or less number of primary rocks, united.

In various states, this forms conglomerates attached to sandstones, under which head it is mentioned. It may be primary or secondary, the former containing the more limited number of ingredients. B. Fragments of primary rocks with limestones. C. Fragments of the same rocks with trap.

This is similar to A. and is found in connection

with trap.

D. Fragments of granite, limestone, quartz and gneiss imbedded in mica schist.

This is found where limestone accompanies mica schist-or where the latter rock and gneiss approximate to granite.

E. Fragments of several primary or secondary rocks, or both, with fragments of trap.

This is a trap tuff, and noticed with the overlying rocks. It is in this and a few similar varieties of the most recent origin that organic remains have occasionally been found.

Some of the finer varieties of these rocks are noticed under the head of argillite, being frequently termed greywacks.

TABULAR ARRANGEMENT

OF

FORMATIONS,

Observed in both Hemispheres (1822)

BY

BARON HUMBOLDT,

Roman numerals are perfixed to the names of those formations, which being very seldom wanting, and consequently extending most generally, may be considered as geognostic horizons.

Primitive Formations.

I. Primitive granite.

Primitive granite and gneiss.

Stanniferous granite.

Weistein with serpentine.

II. Primitive gneiss.

Gneiss and mica-slate.

Granite posterior to gneiss, anterior to mica

slate.

Primitive sienite ?

Primitive serpentine ?

Primitive limestone.

The five latter formations, placed between gneiss and primitive mica slate, are parallel formations.