20 Or MINERAL BEDS, OR STRATA. 
The rocky strata of the globe are seldom parallel, either to the 
surface or to the horizon. It is but a small number of them that 
it would be in our power to examine if this were the case. The 
Himmaleh mountains on the north of Indostan, attain an eleva- 
tion of about 29,000 feet. The mine at Uttenburg, in Bohemia, 
(the deepest in the world) descends 3000 feet below the surface. 
It is probable that it does not reach the level of the sea ; but even 
supposing it to penetrate 3000 feet beneath that level, it is evident 
that but a small number of beds can lie between these limits, 
above and below. The number that would be exposed to view 
in such a country as ours, is still more inconsiderable. Their 
thickness would be represented on an eighteen inch globe, by 
less than that of a single sheet of letter paper — the Himmaleh 
mountains by less than four sheets. 
The strata of the globe are therefore inclined to the horizon, 
and sometimes at very large angles. Their position furnishes con- 
clusive evidence of the violent convulsions by which the earth has 
been agitated and torn. Their edges being turned up to the sur- 
face, series of strata, hundreds and thousands of feet in 
thickness are subjected to our observations within the limits 
of a country that is either level or moderately uneven, and of 
no great extent, and the evidences of. the stratification of the 
rocks are of much more frequent occurrence than if the position 
of the beds were universally horizontal. 
It is sometimes important that the position of the strata with 
respect to both the plane of the meridian and the plane of the 
horizon, should be accurately known. It is ascertained by ob- 
servations, for determining their bearing and dip, of which the 
former i§ measured with the compass, and the latter with an 
instrument called the Clinometer. 
When Geologists first began to notice the position of the rocks, 
they contented themselves with stating the quarter of the heavens 
towards which the strata descended or declined, and in a very 
general way, the amount of declination or descent. When great- 
er precision and accuracy were introduced, it was found most 
convenient to measure and specify the bearing and inclination 
of the strata, and employ the word dip, to point out only the side 
of the line of bearing on which they lie. If a book be placed in 
an inclined position, with the back resting upon a table, the leaves 
will represent inclined strata, a line passing lengthwise along the 
edges of the leaves, will be the line of bearing, and another at 
right angles to this, along the surface of the leaves, will be the 
line of dip. The plane angle, contained between the plane of the 
leaves and the plane of the horizon, is called the angle of incli- 
nation. 
The situation of an incumbent rock, sometimes corresponds 
more or less accurately, to that of the rock or stratum, on which 
it rests, the dip of the two being in the same direction, and the 
angle of inclination also the same. This is what is called a con- 
