. An introduction to geology : intended to convey a practical knowledge of the science, and comprising the most important recent discoveries, with explanations of the facts and phenomena which serve to confirm or invalidate various geological theories. rface exposed to observation nearly sixtymiles in length, and from fifteen to twenty miles in breadth. Themarine beds on which the Wealden rest, must, at a remote period,have been raised, a considerable height above the ocean, and becomedry land, having extensive rivers, lakes, or estuaries filled with freshwater, in which the Wealden beds were
. An introduction to geology : intended to convey a practical knowledge of the science, and comprising the most important recent discoveries, with explanations of the facts and phenomena which serve to confirm or invalidate various geological theories. rface exposed to observation nearly sixtymiles in length, and from fifteen to twenty miles in breadth. Themarine beds on which the Wealden rest, must, at a remote period,have been raised, a considerable height above the ocean, and becomedry land, having extensive rivers, lakes, or estuaries filled with freshwater, in which the Wealden beds were deposited. Again, at a sub-sequent period, the whole must have sunk deep beneath the surfaceof the sea, and been covered by a deposition of chalk and other ma-rine strata, a thousand feet or more in thickness. At a more recentepoch, the chalk, with the subjacent beds of Wealden, were raisedto their present elevation above the neighbouring sea. However thepresent quiescent state of the earth may seem opposed to the admis-sion of such great geological changes, we are irresistibly compelledto resort to these changes for a satisfactory solution of existing phe-nomena. The relative position of the Wealden beds will be understood fromthe annexed The chalk hills of the North and South Downs will be seen sur-rounding the Weald country. Below the chalk is the green sand,marked with waving lines, containing, like the chalk, marine fossilsexclusively. The fresh-water formations of Weald clay and Hast-ings sand and sandstone, rise from under the lower green Weald clay and Hastings sand have generally been representedas distinct formations, but in reality the whole of the Wealden iscomposed of beds of clay, limestone, and sandstone, though in theouter part, marked with dots, the clay predominates. The sand andsandstone predominate in the central parts marked by diagonal lines,extending east and west from beyond Horsham to Hastings. In this IRONSTONE OF THE WEALDS. 193 directi
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Keywords: ., bookcentury1800, bookidintroduc, booksubjectgeology, bookyear1833
