Nov., 1918] Recovery of Vegetation at Kodiak 15 



There is one point of dissimilarity between Katmai and all 

 of the other eruptions cited, which is of great importance in 

 the problem of revegetation. All of these volcanoes are 

 located in tropical countries, while Katmai is on the edge of 

 the subarctic zone. This of itself must compel the process of 

 revegetation to take a widely different course. The differences 

 introduced by the chmatic factor promise, indeed, to become 

 more and more interesting as time goes on, and it becomes 

 possible to make better comparisons of the course of revegetation 

 here and in warmer districts. 



THE GREAT PREHISTORIC ERUPTION OF ALASKA. 



Of all eruptions, the one which presents conditions most 

 similar to that of Katmai is probably the Great Prehistoric 

 Eruption which covered a vast area in the interior of Alaska and 

 the Yukon territory with a thick blanket of ash and pumice. 

 Capps^^ maps an area of one hundred and forty thousand square 

 miles known to have received a deposit of an inch or more of 

 ash. But his figure, large as it is, is not to be taken as an 

 estimate of the area covered, for it is admittedly based on the 

 incomplete data available from a country only partially explored. 

 Near the crater, deposits of this material three hundred feet 

 thick have been reported. This eruption though geologically 

 recent, occurred long before historic records began in North 

 America. Capps" estimates that it is fourteen hundred years 

 old. It is evident, therefore, that the forces of erosion have 

 had full sway. Judging from our experience at Kodiak, vast 

 quantities of this material must have been carried out to sea 

 by erosion. Its original mass may have been much greater 

 than present estimates would indicate. 



It is to this region that one must look for aid in predicting 

 the course of events in the Katmai district. Here the succession 

 of events, in the course of revegetation, must have been some- 

 what similar to that in our area. Unfortunately, however, 

 this region has not yet been studied botanically, and little is 

 known about its revegetation. In many places the ash deposit 

 is covered with a layer of peat, which reaches a thickness of 

 seven feet as reported by Capps^^ But in other places, the 



i^Capps, S. R. An Ancient Volcanic Eruption in the Upper Yukon Basin. 

 U. S. G. S. Prof. Pap. 95 D. 1915. 



" Capps, S. R. An Estimate of the Age of the L^st Great Glaciation in Alaska. 

 Jour. Wash. Acad. Sci. 5: 108-115. 1915. 



