PHYSICAL GEOGRAPHY 307 



found, at intervals of a whole day's journey, some small oases with 

 a denser vegetation, in places where water is present, especially 

 springs which issue from under the edge of the lava-streams. I 

 propose to give here the names of some of these oases and their 

 height above sea-level, and add some notes on their vegetation, which 

 is generally very little known. As almost no notes are published 

 on the vegetation of the plateau I shall avail myself of this oppor- 

 tunity to give a list of the species I collected on some of these 

 oases, as they have never been visited by botanists. Some of these 

 plant-covered patches are only a few square metres in extent, and 

 the largest of them are perhaps as much as a square km. in area 1 . 

 These oases often originate around hot springs, the temperature of 

 which need not be very high somewhat higher, however, than 

 the mean temperature of the locality at which they rise. Thus NW. 

 of Vatnajokull there are oases near Gaesavotn, 929 metres above 

 sea-level, where the springs have a temperature of 5 7C. , and 

 near Marteinsflaeda (744 metres) with spring-temperature of 35V2 C. 

 and near Hitalaug (672 metres) with a temperature of 33V2 C. 

 Gaesavotn is the most highly situated of all the oases that I visited 

 in 1884; plant -growth occurs here in connection with pools and 

 springs; along the margins the vegetation is formed by mosses and 

 Salix herbacea with scattered specimens of Polygonum viviparum, 

 Saxifraga stellaris, Oxyria digyna, Armeria maritima, Cerastinm and 

 Poa, while Carices and Eriophorum form a fringe along the water's 

 edge. Here I collected the following plants: Equisetum arvense 

 var. alpestre, Calamagrostis stricta var. borealis, Aira alpina, Poa pra- 

 tensis, P. pratensis var. alpigena, Poa alpina var. vivipara, Carex in- 

 curva, Eriophorum Scheuchzeri, E. angusti folium, Salix phylicifolia, 

 S. herbacea, Polygonnm viviparum, Oxyria digyna f. pygm&a, Ar- 

 meria sibirica, Saxifraga stellaris f. pygmcea, S. decipiens var. gron- 

 landica, Ranunculus hyperboreus, Cerastium arcticum, C. trigynum 2 . 

 From here I went to Hvannalindir near Kverkfjoll, the nearest 

 oasis towards the east, but it took nevertheless two days (17, 18 Aug.) 

 to reach it, travelling along the northern edge of Vatnajokull; along 

 the whole of this stretch of land there were almost no plants, until 

 at Jokulsa, 734 metres above sea-level, I found in the gravel a fairly 

 large quantity of Cham&nerium latifolium and Oxyria digyna. 



1 In my work "Island, Grundriss d. Geographic u. Geologic", 1906. there is a 

 map showing the desert-boundaries and the oases known. 



2 Determined by Prof. Joh. Lange. 



