This comes under the head of argillite (graywack) where it is also mentioned. G. Quartz sand, with sand from the disintegration of trap rocks. Third Division. Containing fragments of the previous rocks: of a conglomerate structure. Red sand stone conglomerate, or breccia. A. The basis consisting of either of the preceding fine varieties, except F. and G. 2d Div: and containing fragments of quartz only. B. Similar basis, with fragments of one, or of all the preceding rocks, except argillite, with quartz also. C. The same, including F. 2d Div. with fragments of argillite. D. The base G. 2d Div. with fragments of the traps. E. The same basis as var. A. containing fragments of sandstone, with or without fragments of preceding rocks. SYNOPSIS OF COAL. Simple: Carbon nearly pure.. A. Burning with difficulty and without flame: anthracite, when perfect. This modification of carbon contains so little hydrogen as to afford neither naptha nor petroleum on distillation: of course it yields neither flame nor smoke. a. Massive; with a conchoidal shining fracture; of an aspect nearly metallic : is found among primary rocks: passes into plumbago. coal. b. Friable, pulverulent, or scaly. Rare. This and the preceding varieties are found in primary strata; and sometimes in the secondary. The last passes into common coal. d. Columnar, or prismatic. Found in the vicinity of trap rocks, and passes into plumbago. Second Division. Compound Carbon and bitumen. A. Flaming, and burning easily, with smoke. Common coal; occurs massive and slaty united. Several varieties, according to the quantity of bitumen it yields. They pass into bituminous shale and are invariable secondary. B. Very inflammable: leaving little coak; massive or imperfectly laminar: large conchoidal fracture; more or less bright, sometimes dull. Cannel coal, occurs with the secondary coal-and is sometimes cut, like jet. C. Coak, Ashes, and smut: rare and partial modifications, occurring with the trap rocks. Third Division. Lignite retaining marks of vegetable origin. A. Jet, or pitch coal, black amber; hard and compact: pitchy lustre, takes a good polish; occasionally shows the ligneous fibres. Used as fuel. In Aude, in France, 1200 persons are engaged in making ornaments of it. B. Fibrous brown coal; bituminized wood: Bovey coal. The ligneous fibre very distinct; burns with a clear flame. The suturbrand of Iceland belongs to this variety. C. Earth coal, or earthy brown coal; pulverulent, retaining the texture of wood, though compact: burns easily. Known also as Colonge earth or umber. D. Moor coal; friable: nearly the same as brown coal, into which it passes. It breaks on exposure to air. All the preceding varieties occur in the newer formations: mostly in the tertiary and alluvial, occupying extensive tracts, in strata of various thicknesses. Not much used as fuel. E. Basaltic coal: basaltic wood retaining the texture of wood and passing into true coal. Found in trap rocks. SYNOPSIS OF PEAT. Although peat does not properly come under the head of rocks, I do not see a more appropriate place for its Synopsis than the present. It has been spoken of before, and the following are the varieties. A. Loose or powdery, and often intermixed with clay or sand: mountain and heath peat. B. Spongy, imperfect, and containing a large proportion of the roots and fragments of undecomposed vegetables. C. Compact, but still retaining numerous fragments of vegetables, and passing into the former. The most ordinary variety used for fuel. D. Highly compact, with a total loss of vegetable texture. Heavier than the last, and burns nearly like coal, with a considerable flame. More rare than the former. The varieties B. and C. are always in the same deposit, and frequently D, the spongy kind being above and becoming more compact below, exhibiting the progress of vegetable decomposition or the perfection of peat. When wet in their natural position all varieties are soft, and harden by drying. E. Compact generally flaky when dry, and containing fragments, roots, and trunks of trees. Forest peat. F. When wet, a mixture of water and fine powder of peat on drying, very compact. Transported peat; forming fluid bogs. As long as vegetaton is kept up, the peat is renewed after removal: but the process ceases when the vegetating surface is removed, unless it is renewed by nature or artificial means; except in transported peat. Simple. SYNOPSIS OF SHALE. First Division. A. Common Shale. a. Hard, and often not distinguishable from argillite and graywack: occurs mostly with old red stone. b. Fragile, and less laminar than the preceding. c. Tender and Scaly. d. Passing into clay. e. Granular concretionary. |