88 P. A. ØYEN. 



The map of the Lakelet of Skadevand is drawn to the scale 

 of 1 to 10 000, and we find the vertical distance between the 

 altitude curves to be one hundred Norwegian feet, that is about 

 thirty-one metres and a half. The hatched portions of the map 

 represent bare rock, partly covered with débris and fallen rock, 

 and the dotted part shows the area covered by snow-fields of a 

 more or less continuous character. To the south of the lake we 

 meet with a somewhat steep mountain slope covered by a small 

 glacier protruding far into the water of the lake. This glacier is 

 marked in the sketch-map as an offshoot of the snow-field. With 

 regard to the inundations of the valley below the lake, Mr. Mun- 

 DAL, by inspecting the locality, has arrived at the same conclu- 

 sion as that previously expressed, namely, that the small glacier, 

 now only protruding into the lake, may, during periods of wet 

 and cold, increase so as to project right across the outlet, and 

 thus dam up the water. We now see before us this very phe- 

 nomenon of an ice-dammed lake, as variable as climatic condi- 

 tions. 



As an instance of glacier oscillation of that time, we may 

 follow the variation of the Glacier of Nigard. In 1820 Bohr 

 states the distance between the moraine of 1742 — 1743 and the 

 lower end of the glacier to be 542 metres, while at the same 

 time the bare rock adjoining it indicated a decrease of sixty-three 

 metres in the thickness of the glacier. Only a couple of years 

 later, however, Naumann states the distance between the glacier 

 and the moraine to be such as would indicate a decrease of 

 another hundred metres in the length of the glacier. In those years 

 the retrogression of the glacier has been comparatively rapid, if 

 we may rely upon the rough figures given by Naumann. We 

 are, however, justified in viewing the phenomenon as a sure evi- 

 dence that we have entered into a well-marked period of decrea- 

 sing glaciers. 



On the authority of Durocher, it has been generally suppo- 

 sed that the glaciers of the Jostedal were stationary during the 



