The pictorial sketch-book of Pennsylvania : or, its scenery, internal improvements, resources, and agriculture, popularly described . hs crust, yet it is necessary to a proper eluci-dation of what has already been said as well as what is to follow, topoint out some of the changes of position, of fracture, denudation anddisruption which they have undergone. Fig. 18, will probably serveto show the original horizontal appearance of strata, one layer lying 144 OFF-HAND SKETCHES, upon another. Fig. 19 exhibits the usual appearance of stratifiedrocks, lying also in a horizontal position, the lines o
The pictorial sketch-book of Pennsylvania : or, its scenery, internal improvements, resources, and agriculture, popularly described . hs crust, yet it is necessary to a proper eluci-dation of what has already been said as well as what is to follow, topoint out some of the changes of position, of fracture, denudation anddisruption which they have undergone. Fig. 18, will probably serveto show the original horizontal appearance of strata, one layer lying 144 OFF-HAND SKETCHES, upon another. Fig. 19 exhibits the usual appearance of stratifiedrocks, lying also in a horizontal position, the lines of stratificationbeing distinctly marked, dividing the rocks into layers very nearlydetached from each other. This is pe-culiar to all aqueous rocks, and may benoticed in quarries of limestone, andsimilar stratified rooks. From a hori-zontal position, owing to the disturbingcauses previously enumerated, the stratahave in many instances been changedfig. 20. to a vertical position, as shown in fig. 20. In other cases, they are changed to an inverted position by theintrusion of igneous rocks from below, and actually thrown back, as.
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Keywords: ., bookcentury1800, bookdecade, booksubjectminesandmineralresources
