'3 THE POLAR WORLD. 



into the Hvita, or White River. Soon the subterraneous thunder, the shaking of 

 the ground, the simmering above the tube, and the other phenomena which at- 

 tend each minor eruption, begin again, to be followed by a new period of rest, 

 and thus this wonderful play of nature goes on day after day, year after year, 

 and century after century. The mound of the Geysir bears witness to its im- 

 mense antiquity, as its water contains but a minute portion of silica. 



After the Geysir, the most remarkable fountain of these Phlegra?.an fields is 

 the great Strokkr, situated about four hundred feet from the former. Its tube. 



THE STROKKR. 



the margin of which is almost even with the general surface, the small mound 

 and basin being hardly discernible, is funnel-shaped, or resembling the flower of 

 a convolvulus, having a depth of forty-eight feet, and a diameter of six feet at 

 the mouth, but contracting, at twenty-two feet from the bottom, to only eleven 

 inches. The water stands from nine to twelve feet under the brim, and is gen- 

 erally in violent ebullition. A short time before the beginning of the erup- 

 tions, which are more frequent than those of the Great Geysir, an enormous 

 mass of steam rushes from the tube, and is followed by a rapid succession of jets, 

 sometimes rising to the height of 120 or 150 feet, and dissolving into silvery 

 mist. A peculiarity of the Strokkr is that it can at any time be provoked to an 

 eruption by throwing into the orifice large masses of peat or turf ; thus chok- 

 ing the shaft, and preventing the free escape of the steam. After the lapse of 

 about ten minutes, the boiling fluid, as if indignant at this attempt upon its 

 liberty, heaves up a column of mud and water, with fragments of peat, as black 

 as ink. 



