. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. Ca. XVI1L] AKEA OF THE WEALDEN. 35^ ing erect on the spot where they originally grew, the sand having been gently deposited upon and around them; and similar appearances have been remarked in other places in this formation.* In the same division also of the Wealden, at Cuckfield, is a bed of gravel or con- glomerate, consisting of water-worn pebbles of quartz and jasper, with rolled bones of reptiles. These must have been drifted by a current, probably in water of no
. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. Ca. XVI1L] AKEA OF THE WEALDEN. 35^ ing erect on the spot where they originally grew, the sand having been gently deposited upon and around them; and similar appearances have been remarked in other places in this formation.* In the same division also of the Wealden, at Cuckfield, is a bed of gravel or con- glomerate, consisting of water-worn pebbles of quartz and jasper, with rolled bones of reptiles. These must have been drifted by a current, probably in water of no great depth. From such facts we may infer that, Flg- 84T- notwithstanding the great thickness of this division of the "Wealden, the whole of it was a deposit in water of a moderate depth, and often extremely shallow. This idea may seem start- ling at first, yet such would be the natural consequence of a gradual and continuous sinking of the ground in an estuary Or bay, into which a great Sphenopteris gracilis (Fitton), from the -,. -I i-i xi#j j. Hastings Sands near Tunbridge Wells. river discharged its turbid waters. a. A portion of the same magnified. By each foot of subsidence, the fun- damental rock would be depressed one foot farther from the surface ; but the bay would not be deepened, if newly deposited mud and sand should raise the bottom one foot. On the contrary, such new strata of sand and mud might be frequently laid dry at low water, or overgrown for a season by a vegetation proper to marshes. Area of the Wealden.—In regard to the geographical extent of the "Wealden, it cannot be accurately laid down; because so much of it is concealed beneath the newer marine formations. It has been traced about 200 English miles from west to east, from the coast of Dorset- shire to near Boulogne, in France; and nearly 200 miles from northwest to southeast, from Surrey and- Hampshire to Beauvais, in France. If the formation be continuous throughout this space, which i
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1868
