EEPOKT OF BRITISH COMMISSIONERS. 107 



378. It is found that such partly polislied rocks are characteristic 

 particuhuly of the seaward side of the several rookery grounds, and 

 that further inland, and at greater distances from the central parts of 

 the several rookeries, the appearance become less and less well marked, 

 till it at length ceases to be observable. 



379. It is evident that the polishing and wearing down of rocky 

 angles in the manner above described can have occurred only during 



long series of years; but it is also evident that the occupation 

 08 of the same sjjot by large numbers of seals, say once in every 



third or eveji every fifth or tenth year, would be sufficient to 

 render the polishing ])rocess practically continuous. That, in fact, any 

 particular rocky spot, if not occupied for intervals of several or many 

 years, would not in such intervals lose the traces impressed upon it by 

 former occupation, and that, if reoccupied fiom time to time, these 

 traces would become cumulative. Experience gained in connection 

 with the examination of j)olishing due to the glacial period in other 

 regions, impressed on just such rocks as those of the Pribyloff Islands, 

 shows that such polishing is exceedingly enduring, and that the mere 

 action of the weather upon polished rock angles, like those found upon 

 some of the breeding grounds, cannot have perceptibly operated in the 

 direction of their obliteration since the earliest human knowledge of 

 the Pribyloff Islands. Otherwise stated, it may be safely asserted, 

 that while affording no valid evidence of recent occupation, such traces 

 give invaluable evidence as to the whole area at any time long occupied 

 by large numbers of seals during the past few hundred years. 



380. In consequence of the want of actual information as to the extent 

 of seal occupied ground about the various breeding places on the Pri- 

 byloff' Islands in various years, a veiy general tendency is apparent, 

 even among those who have been familiar with the islands for several 

 years, to magnify the conditions of the past at the expense of the pres- 

 ent, and free scope is often given to the imagination in describing the 

 former extent of various rookeries and hauling grounds. An excellent 

 corrective to generalizations of this kind was found, however, in noting 

 the bare or lichen -covered surfaces of the scattered rocks. The climatf;, 

 as well as the rock surfaces of the Pribyloff" Islands, are well adapted 

 to the growth of lichens, but where seals have been in any considerable 

 numbers, no lichens are found on any surface over which they can climb, 

 or wdiich has been within the reach of their flippers. A knowledge of 

 the very slow growth of lichens was sufficient to indicate that where 

 such accessible rocks were well lichen-covered, seal life must have been 

 but scantily, if at all, represented for a long term of years. 



381. An observation of this particular fact, continued from rookery 

 to rookery over both islands, showed that the lichened rocks often 

 extended quite to the limits of the ground still annually kept bare of 

 grass by the seals. By this statement, it is not meant to affirm that 

 the lichened rocks and stones were always and everywhere contermi- 

 nous with the limit of the bared ground, but that in many cases easily 

 accessible points of ground touched these limits, both on St. Paul and 

 St. George, and thus proved that the seal-frequented area had not con- 

 tinuously overpassed the actual limits for a considerable number of 

 years, and that vague statements to a contrary effect were necessarily 

 erroneous. This was particularly noted on West Zapadnie Rookery, on 

 certain parts of the Keef rookeries, and those of North-East Point on 

 St. Paul, and on the Little Eastern Rookery on St. George; but as a 

 criterion, it was in a lesser degree distinctly observed on nearly all of 

 the breeding- grounds. 



