GENERAL DESCRIPTIONS AND FACTS.

13

allowance is made for the probable greater height ofMr Stevenson’s datum.

14. A terrace, long recognised by local geologistsas of this character, extends irregularly along bothsides of the Firth of Forth , in some places 20, inothers 26 feet. It is noted for the shells found init. It appears conspicuously between Hewhavenand Granton, where it is 20 feet (§ 119). In anarrow stripe on the opposite shore, but at 26 feet,it forms the site of the principal part of the town ofKirkaldy . At Portobello it expands into a sandyplain, the upper extreme of which is 26 feet. Inreality, the several points here referred to expresstwo distinct terraces, each commemorating a pauseof the sea. The stripe of ground on which the prin-cipal parts of Dundee are built, extending betweenthe Firth of Tay and the base of the neighbouringheights, is precisely a repetition of the 20-feetterrace.

15. My examples from the south are not nume-rous, in consequence of limited opportunities. Imay, however, cite a specimen of the 32-feet ter-race, extending along the south bank of the Eslc atLongtown, having Netherby Castle seated upon it;an example of the 11-feet alluvium on the Kibble,at Preston; and the great Chichester plain alreadyalluded to, which rises at its inner extremity to 42feet. The low lands beside the Thames , including thesite of some of the lower parts of London , Southwark,