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The formations which are referrible to a period that succeeded the 

 most recent tertiary epoch, and preceded the period when the earth 

 was inhabited by man, and which the author terms the post-tertiary 

 formations, may be divided into the so-called diluvium, the erratic 

 blocks which have been transported by the action of glaciers, and 

 the remains of ancient sea-beaches. 



The so-called diluvium usually consists of clay and erratic boul- 

 ders, of which the latter are often identical in substance with the 

 rock of some more or less distant mountain- chain ; and in such cases 

 may be considered to have been derived from the chains in question. 

 Since deep valleys, of anterior date to the diluvium, often intervene 

 between the rocks in situ and the districts over which the derivative 

 boulders are spread, the transport of these masses has in later times 

 been attributed by geologists to the action of floating icebergs, an 

 action which, according to the observations of Scoresby and others, 

 is fully adequate to remove from the Arctic to more temperate re- 

 gions great masses of earth and rock, and actually operates every 

 year in the manner stated to an incredible extent. Were the bed 

 of the ocean in which these icebergs, on melting, have deposited, 

 and continue to deposit, their rocky freight, to be now elevated above 

 the sea-level, it would present a striking resemblance to the so-called 

 diluvium. What further tends to confirm this theory is, that the 

 diluvium is often found to contain the remains of Mollusca, partly 

 of arctic origin ; and these are frequently in a state of perfect pre- 

 servation ; a fact which renders it probable that these remains have 

 not been removed to any great distance from their native habitat. 



The consequence of supposing numerous icebergs to have floated, 

 at a former period, into latitudes in which icebergs are never seen at 

 present, is, that the temperature of these regions and of the whole 

 earth at that period was lower than it is at present ; and the less 

 the distance to which the icebergs were floated from the glacier they 

 were originally launched from, the further must the then frigid have 

 encroached on the now temperate zone. 



The erratic blocks which are found at various elevations on the 

 declivities of the Alps, and which sometimes form large mounds 

 placed transversely to those declivities, resemble in that respect the 

 morains formed by glaciers ; and hence it has been inferred that it 

 is by the action of glaciers that these alpine boulders have been 

 transferred to their present sites. Supposing that to have been the 

 case, the ancient glaciers must have extended to a much lower level 

 than the modern glaciers ; and the temperature of the Swiss valleys 

 must have been lower than it is at present. The glacier theory 

 therefore leads to the conclusion, that when these ancient morains 

 were formed there existed a frigid climate in the now temperate 

 zone. 



There have been observed in many and very remote parts of the 

 world, at considerable elevations above the present sea-level, ex- 

 tending through great distances of country, long terraces of trans- 

 ported materials, such as sand, clay, and pebbles ; and these terraces 

 geologists have agreed in considering as the remains of ancient sea- 



