An Interpretation of Bunsen's Geyser Theory

Abstract

The geyser theory of Bunsen appears to the writer to be imperfectly presented, as found in English and American textbooks on geology. Two erroneous assumptions are to be found. First, that the relief of pressure assumed in this theory is due to an overflow from the top of the water column or to expansion into a basin with resultant shortening of the column. Many splendidly functioning geysers have no visible overflow preceding an eruption and very many have no basins. Second, it is assumed that the mere lifting of the upper portion of the water column without overflow would relieve the pressure below sufficiently to bring on an eruption. As long as the head remains the same, obviously there could be no such relief of pressure. The observations of Bunsen and Descloizeaux upon the Great Geyser of Iceland established the existence, about halfway down in the tube, of what may be called the "critical zone." Here the actual and boiling temperatures come very close together as the conditions for an eruption are being slowly attained. Steam bubbles are first formed in the lowest depths of the system and when powerful enough slightly elevate a portion of the water at the critical zone, bringing it to a level where it can flash into steam, thus starting the eruption and relieving the pressure on the lower portion of the water column.