DROWNED ANCIENT ISLANDS — HESS 



283 



does extend to 45° N. to 165° W. Some of the seamounts in the Gulf 

 of Alaska described by Murray (1941) almost certainly are guyots, 

 whereas others appear to be of a different character. Twenty bona 

 fide guyots were encountered at sea by the writer and some 140 more 

 are indicated by soundings on Hydrographic Office charts and docu- 

 ments. Considering sparseness of deep-sea soundings in parts of the 

 area mentioned above, it is likely that a large number of undiscovered 

 ones are present. 



FiGUBE 2. — Index map showing area included in figure 1. 



PHYSICAL FEATURES OF GUYOTS 



One of the best profiles obtained across a guyot was one encountered 

 south of Eniwetok on October 6, 1944, in latitude 8° 50' N., longitude 

 163°10' E. This guyot is about 35 miles in diameter at the base, and 

 the truncated upper surface is about 9 miles in diameter. The top is 

 remarkably flat at a depth of 620 fathoms.^ The outer rim of the top 

 is beveled by a gently sloping shelf 1 or 2 miles wide (slope 2° to 3°). 

 The outer margin of the gentle slope is about 70 fathoms deeper than 



* All soundings mentioned in this paper are uncorrected for salinity, temperature, and 

 pressure, and were talien with fathometers set to a speed of sound in the sea water of 

 4,800 feet per second. The corrections would be too small to be of signiflcance in this 

 discussion. 



