. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. Ch. DIP AND STRIKE. 53 vegetable remains, are curved again and again, and even folded into the form of the letter Z, so that the same continuous layer of coal is cut through several times in the same perpendicular shaft. Thus, in the eoal-field near Mons, in Belgium, these zigzag bendiugs are repeated four Fig. Zigzag flexures of coal near Mons. or five times, in the manner represented in fig. 67, the black lines repre- senting seams of coal.* Dip and strike
. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. Ch. DIP AND STRIKE. 53 vegetable remains, are curved again and again, and even folded into the form of the letter Z, so that the same continuous layer of coal is cut through several times in the same perpendicular shaft. Thus, in the eoal-field near Mons, in Belgium, these zigzag bendiugs are repeated four Fig. Zigzag flexures of coal near Mons. or five times, in the manner represented in fig. 67, the black lines repre- senting seams of coal.* Dip and strike.—In the above remarks, several technical terms have been used, such as dip, the unconformable position of strata, and the anticlinal and synclinal hues, which, as well as the strike of the beds, I shall now explain. If a stratum or bed of rock, instead of being quite level, be inclined to one side, it is said to dip; the point of the compass to which it is inclined is called the point of dip, and the degree of devi- ation from a level or horizontal line is called the amount of dip, or the Fig< 68. angle of dip. Thus, in the annexed diagram (fig. 68), a series of strata are inclined, and they dip to the north at an angle of forty-five degrees. The strike, or line of bearing, is the pro- longation or extension of the strata in a direction at right angles to the dip ; and hence it is sometimes called the direction of the strata. Thus, in the above instance of strata dipping to the north, their strike must necessarily be east and west. "We have borrowed the word from the German geologists, streichen signifying to extend, to have a certain direction. Dip and strike may be aptly illus- trated by a row of houses running east and west, the long ridge of the roof representing the strike of the stratum of slates, which dip on one side to the north, and on the other to the south. A stratum which is horizontal, or quite level in all directions, has neither dip nor strike. It is
Size: 2193px × 1139px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1868
