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18 ON CHANGES IN THE DISPOSITION should we easily recognise one feature of the countries most familiar to us. Of the filling of lakes, the whole world presents examples, and we see the process going on every uay. Being a subject which concerns physical geography, we may procure abundant information on it, in the works of antient and modern geographers. The boun daries of the Caspian are every day contracting, and the neighbouring deposits of shells and mud indicate its former probable communication with the Aral. The Baikal is diminishing rapidly : and the valley of Cash- mire still contains some small lakes, the remains of that which once filled the whole of this basin : as is equally supposed of the valley of Nepaul. In Mexico, in 1520, Cortez found two lakes, the one salt and the other fresh: there are now five smaller ones, produced by the accession of new land ; and the whole valley, containing two hundred and forty-four square leagues, of which but one tenth is now water, was formerly a single lake. Here, I need scarcely repeat, we trace the origin of those lacustral “ formations,” concerning which geologists have made such confusion; as, in the cases just quoted, we equally find those alluvia of the ocean which have so often been confounded with them under the term “Tertiary.” If I unwillingly take room for further examples, since thus are books too easily written, teaching nothing, as is the usage, the same is true of the lake of Geneva, diminishing daily; of those of Thun and Brientz, now separated by an alluvial plain ; of the valley of the Aar, once a receptacle of water; of Loch Tumel, in our own country, now re duced to less than half its original size ; of Loch Ran- noch, once flowing at the foot of Mount Alexander ; of Crummock and Buttermere, now separated like the Swisslakes just mentioned ; andof Loch Lomond, where