This study examines whether or not the visual 

 classification of icebergs is a meaningful way to 

 classify the height to draft ratios of these bergs. 

 Based loosely on Murray (1968), the icebergs of 

 this study were separated into five general cate- 

 gories based on gross visual shape characteristics. 



1. Tabular bergs were horizontal, flat-topped 

 bergs with a length to height ratio generally 

 greater than 5 :1. 



2. Broken tabular bergs were those that were 

 mainly horizontal but whose surface was highly 

 fractured, with a length to height ratio generally 

 greater than 5 :1. 



3. Pinnacled bergs had a large central spire or 

 a pyramid of one or more spires dominating the 

 shape. 



4. Domed bergs had a large, smooth rounded 

 top which had once been submerged. 



5. Drydocked bergs had an eroded U-shaped 

 slot cut by wave action surrounded by high verti- 

 cal walls or pinnacled. 



The mean height to draft ratio for each of the 

 five visual classes was computed and compared 

 statistically to the mean ratio for all other classes. 

 The null hypothesis is that there is no significant 

 difference between the height to draft ratios for 

 the visual classes of icebergs. 



The height to draft ratios for the icebergs 

 studied ranged from 1:1.28 to 1:10.56 (Tables 

 1 through 5). The 1:1.28 value was in line with 

 previous measurements, but the 1 :10.56 value was 

 smaller than any of the previously reported 

 ratios. The 1 :10.56 ratio was associated with a 

 domed berg where the rounded above-the-water 

 portion had the maximum mass in the minimum 

 height. To attain this value the underwater por- 

 tion probably had a taproot-like formation. 



The tabular and broken tabular (Tables 1 and 

 2) had almost identical characteristics. These 

 were the most massive of the bergs, having 

 lengths which were observed to reach 600 meters 

 in this study and much larger in other studies. 

 The mean heights for the tabular and broken 

 tabular were 28.3 and 27.7 meters respectively; 

 the mean drafts being 108.0 and 107.1 meters 

 respectively. Of course, the height to draft 

 ratios were quite similar also, being 1 :4.46 for 

 the tabular and 1 :4.26 for the broken tabular. 

 It appears that generally all bergs which were 

 dominated by a horizontal dimension can be 

 grouped together in respect to their draft ratios. 



Table 1. Height to draft ratios for tabular 

 bergs 



Height 

 (meters) 



Depth 

 (meters) 



Ratio 

 (1: ) 



tabular bergs 



Height 



(meters) 



Depth 



(meters) 



Ratio 



(1: ) 



Pinnacle bergs (Table 3) and drydock bergs 

 (Table 4) also appear to have been quite similar 

 to each other. These, bergs had great height with 

 comparatively little mass. The average height 

 to depth ratios for pinnacle bergs was 1 :2.31 com- 

 pared to 1 :2.41 for drydock bergs. 



Table 3. Height to draft ratios for pinnacle 

 bergs 



72 



