DEOWNED ANCIENT ISLANDS OF THE PACIFIC BASIN 



By H. H. Hess 

 Department of Geology, Princeton University 



PART I. DESCRIPTION 



A large number of curious, flat-topped peaks have been discovered 

 scattered over millions of square miles in the Pacific basin. These 

 peaks are roughly oval in plan and their slopes suggest volcanic cones. 

 The remarkable feature about them is that they are truncated by a 

 level surface which now stands approximately 750 fathoms (4,500 

 feet) below sea level. For convenience in discussing these submerged 

 flat-topped peaks which rise from the normal ocean floor, the writer 

 will henceforth call them "guyots" after the nineteenth-century 

 geographer, Arnold Guyot. 



Betz and Hess (1942) discussed the major features of the floor of 

 the North Pacific. This was in the nature of a broad areal reconnais- 

 sance of the largest features of this extensive region. Since 1942, 

 Hess has spent 2 years at sea in the western Pacific and has thus had 

 the opportunity to fill in some details which bring to light many new 

 relationships and necessitate some modification of ideas originally set 

 forth. The data presented in this paper were obtained on random 

 traverses incidental to wartime cruising on the U. S. S. Cape Johnson. 

 What passed beneath the ship was recorded but it was not feasible to 

 investigate further such interesting features as were encountered. 

 Nevertheless it is evident that much information can be obtained on 

 the geological history of an oceanic area by judicious use of available 

 techniques. It is a vast and intriguing field for research under more 

 auspicious peacetime conditions. 



SCOPE or PRESENT INVESTIGATION 



From random sounding traverses across or merely grazing guyots 

 an attempt will be made to construct a picture of their physical fea- 

 tures. The data collected on the cruises of the Cape Johnson have 



* Presented before the Section of Tectonoph.vsics, American Geophysical Union, In 

 Washington, D. C, on May 27, 1946. Reprinted by permission from American Journal 

 of Science, vol. 244, November 1946, with added text and illustrations. 



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