ap a C€0 ings of the British Association. , 
Square, Glasgow. On the 20th | of January, 1834, a terrible 
earthquake occurred in New Grenada, by which the large towns 
of Popayan and Pasto, were entirely demolished, and many thou- 
sands perished. On the 21st of September, 1834, Mr. Hamilton 
experienced a most severe shock, in which the movements of the 
earth were entirely vertical, and seemed to take place twice eve- 
ry second. He mentions also, the terrible earthquake on the 
coast of Chili, February 5, 1835, by which the seaport of Con- 
ception and 'Talcahuano, the capital of the province, were totally 
destroyed. 'The sea then retired several times to a great distance, 
and returned in immense billows. It is believed that new banks 
were then thrown up from its bottom, and that it was on one of 
these, that the Challenger, ship of war, was wrecked a few 
months after. | 
M. Agassiz made a communication on the subject of glaciers 
and boulders in Switzerland. He particularly drew attention to 
facts relative to the mode of the movements of the glaciers, which 
he attributes to the continual introduction of water into all their 
minutest fissures, which, in freezing, constantly expands the mass. 
The effects of the movement produced by this expansion, upon 
the rocks beneath the ice, are very remarkable. The bases of the 
glaciers, and the sides of the valleys which contain them, are al- 
ways polished and scratched. The fragments of the rocks that 
fall upon the glaciers are accumulated in longitudinal ridges on 
the sides of the ice, by the effects of the unequal movement of its 
middle and lateral masses. The result is longitudinal deposits of 
stony detritus, which are called morains ; and as the glaciers are 
continually pressed forwards, and often in hot summers melted 
back at their lower extremity, it results that the polished surfaces, 
occasioned by friction on the bottom and sides, are left uncovered, 
and that the morains, or curvilinear ridges of gravel, remain upon 
the rocks formerly covered by the ice, so that we can discover by 
the polished surfaces and the morains, the extent to which the 
glaciers have heretofore existed, much beyond the limits they now 
occupy in the Alpine valleys. It even appears to result from the 
facts mentioned by Prof. A., that enormous masses of ice have, at 
a former period, covered the great valley of Switzerland, together 
With’ the whole chain of the Jura, the sides of which, facing the 
Alps, are also polished, and interspersed with angular erratic rocks, 
resembling the boulders in the morains; but so far different, that 
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