SCIENTIFIC RESULTS OF THE KATMAI EXPEDITIONS OF THE 

 NATIONAL GEOGRAPHIC SOCIETY. 



V. THE NITROGEN CONTENT OF VOLCANIC ASH IN 

 THE KATMAI ERUPTION OF 1912. 



J. W. SHIPLEY, 

 Chemist of the 1917 Expedition. 



The opportunity to study the revegetation of a large area 

 buried by volcanic ash comes but rarely. When in June, 1912, 

 following several explosive eruptions, Mt. Katmai ejected 

 from its crater about five cubic miles of ash and pumice and 

 distributed it over the adjacent region to a depth of fifteen feet, 

 gradually diminishing until at Kodiak, 100 miles to the east- 

 ward, it covered the island with a layer of fine ash ten inches 

 deep, such an opportunity was presented on a scale unequalled 

 by any volcanic eruption since the dawn of interest in such 

 matters. All vegetation near the volcano was smothered and 

 killed, leaving large areas covered with a finely divided soil 

 which, while perhaps containing the mineral requisites necessary 

 for plant growth, was absolutely free from organic matter and 

 micro-organisms. An abundant rainfall, and climatic con- 

 ditions favoring the growth of a diversified flora, made this 

 region a fertile field of observation. Flanked on the south and 

 west by the abundant pre-eruptive flora, while here and there 

 throughout the destroyed area oases of plants are preserved, 

 this barren area will become, in 'time, again clothed with 

 vegetation. 



The several expeditions of the National Geographic Society, 

 sent out under the direction of Dr. R. F. Griggs, had as their 

 primary object the observation of the revegetation of this 

 remarkable region. It soon became apparent that one of the 

 principal controlling factors, in the revegetation problem, was 

 the supply of nitrogen as a necessary constituent of plant 

 growth. Consequently the 1917 expedition was equipped with 

 the necessary materials and apparatus for making field determi- 

 nations of the ammonia and nitrite nitrogen content of the ash, 

 and for collecting samples with a view to further analysis in 

 the laboratory. This work was placed in charge of the author. 



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