22

THE CHALK RANGE.

with slight curved lines, apparently as in the pinna, marking theprogressive growth of the shell-. Those shells which lay in thechalk were of a calcareous substance striated or fibrous at rightangles to the surface of the shell: but those specimens which laynear flints, were in some degree silicious, a portion resisting theaction of acids, and retaining their form, though so honeycombedas to be easily crushed in the fingers. Some fragments werefound in the middle of black flints; not imbedded, but perfectlyimmersed in the silicious substance.

H aving thus described the strata and their contents, it remainsto mention their position, and that of the adjacent clay strata.The chalk strata lie inclined to the horizon at an angle of nearlyseventy degrees, dipping north, and their inclination seems veryregularly to follow the line of the hills themselves. 11 ' WhereverI have been able to see the strata in a fair section, this greatinclination appears constant, and the whole mass has been movedapparently at once, without any fissure or chasm in consequenceof it; for the fissures already described to be filled in many partswith flint, bear certain marks of having existed previous to theperiod of the subversion of the whole mass.

The chalk is not the only substance which has been thusoverset; for the clay strata to the north and south of the chalk,to the extent of about a quarter of a mile to the north, and

* Mr. Webster has discovered that this inclination of the strata varies much in differentparts of the island. In a pit on the north side of Brading down, the strata are quite per-pendicular, though on the south side of the same pit, the strata are a little inclined to thsouthward. In the wide part of the range, between Apes down and Shorwell, the strataabout Apes down are very highly inclined, while at Shorwell they are almost horizontal.At the Needle point the strata are also inclined about 70°, but on the south side ofScratchell’s bay, they have a much lower inclination.