64 



ON GEOLOGY. 



rolled or violently distorted, or deprived of their natural contour, such re- 

 mains have not been brought to their present beds from a distance ; but 

 that the deluge must have been sudden, and overtaken them in their natural 

 resorts ; and hence may, in many cases, have swept away all the individuals 

 of a species in a common calamity. 



There is, however, a great difficulty with some naturalists in conceiving 

 that such animals as the elephant, the tapir, the rhinoceros, the hippopota- 

 mus, the mammoth, or mastodon, animals now only found in the torrid re- 

 gions, could have existed in these northern parts of the globe. M. de Mar- 

 schall endeavoured by one sweeping stroke of the fancy to solve this, as 

 well as that of the extraordinary fragments in which they are often imbed- 

 ded, and held out that the whole have fallen at different times, like meteoric 

 stones, from heaven.* The real difficulty, however, vanishes, in a consider- 

 able degree, if not entirely, when we reflect, that although the torrid re- 

 gions furnish us with some of these genera, they do not appear in any in- 

 stance to contain the same precise species as are traced among the large 

 fossil quadrupeds of the northern and colder parts : and hence it is no argu- 

 ment, that because the habits of the extant species do not qualify them 

 for a residence in these latter regions, such situations might not have fur- 

 nished a comfortable home to the species whose remains are found among 

 us. The fossil species do not differ less from the living to which they make 

 the nearest approach, than various animals that are familiar to us do from 

 others that belong to the same tribes, and which are found under one 

 species or other, over the whole world. The race of horses, of swine, or 

 of sheep, furnishes us with abundant examples of this remark : and that of 

 dogs affords perhaps a still more striking illustration ; for while under one 

 form, that of the isatis or Arctic fox, the canis Lagopus of Linnaeus, we 

 find it in the northernmost coast of America, and even the frozen sea, living 

 in clefts, or burrowing on the naked mountains, and in that of the almost 

 infinite varieties of the c. familiaris^ or domestic dog, in the bosom of our 

 Own country, — in the form of the c. aureus^ chacal or jackal, we meet witli 

 it in the warmest parts of Asia and Barbary, prowling at night in flocks of 

 one or two hundred individuals. 



The extensive turbaries or peat-fields, which are so common to 

 many parts of Europe, are produced by an accumulation of the remains of 

 sphagnum and other aquatic mosses. These surround and cover up the 

 small knolls upon which they are formed ; or, in many places, descend 

 along the valleys afler the manner of the glaciers of Switzerland ; but while 

 the latter melt away every year at their lower edges, the mosses are not 

 checked by any obstacle in their regular increase ; and as such increase 

 takes place in determinate proportions, by sounding their depth to the 

 solid ground we may form some estimate of their antiquity. 



The ordinary rise of those extensive ranges of downs, which are seen 

 skirting the coats of many countries, and especially where the shore is not 

 very bold, is a mixt effort of sea and wind. To produce this, however, the 

 soil that the sea washes over must consist of sand. This is first pushed in 

 successive tides towards the shore ; it next becomes dry, by being left there 

 at every reflux of the sea ; and is then drifted up the beach, and to aconsider- 

 able distance from the beach, by the winds which are almost always blow- 

 ing from the sea, and often in whirls or eddies ; £ind are at length fixed 

 by the growth of wild plants, whose seeds are in Hke manner wafled about 



* Becherches sur I'Ori^ne, &c. Geissen. I8U2. 



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