is to be made, it is probable that the coal may extend er it; but if the dip is in the contrary direction, the ch ought not to be undertaken, since experience has n that it would be useless.

Fig. 29.

In

sidera

are co reason

The

undula

he reason will be understood by fig. 29, where 1 2 3 e a series of coal strata, dipping towards b. The unormable strata c c, are sandstone, lying over the coal. , suppose the coal vein 4, makes an outcrop at that , on the estate of A, adjoining the estate of B, which Cowards b, then it is apparent that A would find only a t of the vein 4 on his estate, and that it would be useto search in the direction of d for coal, since the dip is sufficient to prove that none exists there, unless, in, another coal field should be found. Whereas, on the e of B, though there might not exist an outcrop, still lip of that on the estate of A would make it highly able that B would find coal on his estate, though it nt be too deep for working.

We have observed, in another place, that coal has selor never been found in hot climates. According to Bakewell, this mineral has rarely been discovered bethe latitudes of 35° and 65°. It, however, exists in province of Canton, in about the 30th degree of latiIn this country, the great coal ranges appear to lie een the latitudes of 40° and 45°.

cipitous they are

is found

eral leve

dications of Coal. Although it is not certain that coal s at any given place until it is actually found, still e are indications which might perhaps warrant the exe of a search, by boring in districts where coal has ☛ been discovered. These indications are various, and int them out requires much knowledge and experience is subject.

England, Mr. Farey states, that the coal districts into clay, and are generally of an inferior quality. en laid down to pastures, small daisies and insignificant Es are more disposed to prevail than grass.

grained rious size differs fro the coal s

The sl

little from

In En

with coal

cause it is

tricts. R

mations, a

are sunk

sandstone

Bakewell

position of lar quartz

what the

or gray sto

cific gravi

equal bulk yields abo

that kin name is sa

bably beca

regular an

graphic sto

whole form

thickness.

men, and c

these districts, water is generally procured at incon-able depths, and when the faults are numerous, springs common, and range in a line with the fault, for the on already explained.-See Fault.

The face of the country where coal exists, is generally lating, the hills being rounded and not mural or preous, and the valleys gently sloping and not deep as are in granite formations. Sometimes, however, coal und in hills more than a thousand feet above the genlevel of the country.

rata which indicate Coal. In England and Wales, generally reposes on a series of beds called millstoneand shale. The millstone-grit is merely a coarse ned sandstone, consisting of quartzose particles of vas sizes, agglutinated by an argillaceous cement. This rs from the sandstone that is found above and between coal strata, chiefly in its greater induration.

he shale is a dark colored slaty rock, which differs from the slate-clay beds found among coal.

. England, secondary limestone is often associated coal. This is called carboniferous limestone, bee it is generally found in coal or carboniferous dis

3.

Red marl is also a common attendant on coal forons, and indeed, is so common, that few coal shafts sunk without piercing through it. This is a kind of stone cemented with clay and colored with iron. Mr. ewell supposes that it has been formed by the decomion or disintegration of trap, greenstone and granuquartz. Coal is also accompanied with thin strata of t the English call iron-stone. This is a dark brown ray stone, of an earthy appearance, but of great spegravity, being about three times the weight of an l bulk of water. This stone is smelted for iron, and is about thirty per cent. Another attendant on coal at kind of limestone, in England, called lias. This e is said to be a corruption of the word, layers, proy because the strata of this rock are generally very lar and flat. The finer kinds of lias answer for lithohic stones. This rock alternates with lias clay, the le formation sometimes being several hundred feet in kness. This clay is highly impregnated with bituand contains much sulphuret of iron so that when

nce ignited it will continue to burn until the sulphur and itumen are consumed. Several other minerals are found à coal beds, in greater or less quantities, in the English ines, but those enumerated are the most common.

The annexed diagram, fig. 30, showing the different rata as they occur in a coal field near Mamsbury, will lustrate the manner in which most of these minerals are laced with respect to each other.

Fig. 30.

Riv

T

10

9

8

7

101

The lowest stratum, or that on which the others are laced, as within a dish, and which also rises the highest, arked 1, is Old red sandstone. 2, Carboniferous limeone. 3, Millstone-grit. 4 4, Coal seams. 5, Coarse andstone. 66, Red marl, or new red sandstone. 7, Lias. Oolite.

In this country, although several of the strata occurring ith European coal are wanting, still it is found to be asociated with minerals of the same general characters. n Virginia, the strata which cover the coal are sandone and clay-slate, the latter often exhibiting vegetable mpressions. The coal mines of Ohio, are situated among rata of limestone, sandstone and clay-slate.

The following section and description is from Dr. Hilreth's valuable communication on the coal deposites of ne valley of the Ohio, contained in Silliman's Journal for Tov. 1835.

Dr. Hildreth's paper not only relates to the Geology, ut also to the Topography, and Geography of the Ohio, Valley. It is illustrated with a map, several views, and any wood cuts delineating organic remains, and is among ne most valuable and interesting communications on these ubjects ever made to the American public.

3

1. San

2. Coa sively wo

3. Bit

This, bot plants. eighth of

Section of the Coal strata at the Salines on Kenawha iver, Ohio. The strata beginning at the deepest are as follow:

2. Coal. Six feet thick. It is bituminous and is extenely worked for several hundred feet under the hills.

. Bituminous Shale, and slaty shale, forty feet thick.

is both slate and shale is filled with extinct species of