On the Glaciers and Climate of Iceland. 130 



records, the extension of the glaciers has been the same as 

 at present. 



But if we next look back into those periods regarding 

 which we obtain information by geological monuments alone, 



periods during which the average temperature of the earth 



was perhaps somewhat higher than at present, — and if we 

 reflect on the slow rising of the whole island, we may suppose 

 that the climate of the surrounding ocean would then have 

 prevailed on this land, its surface having been much smaller, 

 and its hills lower than at present. Under such conditions, 

 during the formation of the island, no glaciers could have 

 existed ; and it is only at a later period, when the hills had 

 attained the necessary height, that the glaciers could, for the 

 first time, have extended over certain regions their rigid 

 wintry covering, which now appears to be of an everlasting 

 character. 



It is well known, that glaciers constantly produce polished 

 or smoothed sm-faces on their lateral containing walls, and 

 on the beds along which they advance. These, there is no 

 doubt, may be, and frequently are, confounded with those 

 foi'med by the drift ice. 



The reticulated patterns, already mentioned, formed, on 

 the smoothed or polished rocTiS, by mutually-intersecting 

 lines, cannot possibly be explained by glaciers, as these must 

 necessarily push on the grinding material interposed between 

 their base and the solid rock, in a perfectly determinate di- 

 rection. It has also struck me, and it appears worthy of 

 remark, that nowhere in the immediate neighbourhood of 

 the Arnarfell- Jokull was a trace of such [smoothed surfaces 

 to be seen, whilst they are often to be met with on the 

 coasts. At the same time, it is to be recollected that rocks of 

 a durable character are not frequent in that neighbourhood. 

 If we turn yet once more our eyes to the past, and take a 

 brief review of the results we have obtained, we shall per- 

 ceive, on the one hand, the greatest probability that, in ante- 

 historical periods, for the measui'ement of which we are ut- 

 tei'ly devoid of any standard, the climate of Iceland may have 

 been more mild than at present, and have been adapted for 

 a more coiiiplete vegetation ; and also, on the othei' hand, 



