146 THE OCEAN FLOOR 



many colleagues, may be set forth in few words. The 

 deep-sea bottom abounds with evidence of submarine 

 volcanic activity. Volcanic minerals — and not merely 

 fragments of pumice — are normal components of red 

 clay, beds of lava are not uncommon, and the sub- 

 marine ridges, as well as the islands crowning them and 

 all the innumerable islands of the South Seas, testify 

 to the prevalence of submarine volcanism. Add to this 

 the novel idea that the Mid-Atlantic Ridge is due to 

 enormous extrusions of magma during the Tertiary 

 Age, and we can well conceive of the deep-sea bottom 

 as a volcanological laboratory on a gigantic scale. 



Now, we know that eruptions of volcanoes on the 

 continents are very often accompanied and followed by 

 exhalations of carbon dioxide and fumes of hydro- 

 chloric acid, sulphur dioxide, and sulphuric acid. The 

 South American volcano Purace is reputed to exhale 

 about 30,000 tons of hydrochloric acid a day, and from 

 the Valley of the Ten Thousand Smokes near Katmai 

 one million tons of hydrochloric acid are said to be dis- 

 charged annually, even now, 40 years after the great 

 eruption. It would therefore be difficult to deny that 

 submarine volcanoes likewise give off acid fumes. In 

 point of fact, the hot magma welling up through the 

 ocean floor encounters ice-cold water rich in chlorine. 

 It is reasonable to assume that at this encounter 

 hydrolysis must occur on a vast scale, releasing 

 enormous quantities of mineral acids and carbon 

 dioxide. 



