250 Professor R. A. Daly— 



amount, but also by the state of preservation of the strand marks. 

 Allowing for lithological differences, cliffs, benches, caves, and 

 chasms have comparable strength of development in the two regions, 

 in each of which the sea must have worked a relatively long time 

 at the 20 ft. level. Since the shift of level the surf has destroyed 

 a part of each bench in Samoa, therewith doing work roughly equal 

 to the destructive wave-work already performed on equally hard 

 rocks in Maine. 



Difficulties of an Inductive Study of Records. — The hypothesis 

 of a eustatic change must meet the obvious test of matching the 

 facts observable on the shores of every continent and nearly all 

 islands. That the application of the test is not easy will be clear 

 from the following considerations. 



1. Most shores have not been studied with requisite thoroughness. 

 The compilation of the published, apj^ropriate records, incomplete 

 as they are, is a herculean job. Apart from the time and physical 

 labour involved, the compiler is baffled by the psychology of many 

 authors, who have observed in the field and then written their 

 records under- the more or less unconscious control of the uplift 

 hypothesis. Relevant and perfectly accessible facts have therefore 

 not been noted. Moreover, the selection of data in statistical study 

 has its own obvious danger for the compiler. 



2. Writers have not always been careful to give the datum from 

 which the level of each " raised " strand was measured. In general 

 " sea-level " is mentioned without specifying mean level or high- 

 tide level or any other unequivocal datum. The omission is serious 

 for the compiler dealing with a shift of only 20 feet. 



3. The marks of a higher stand of sea-level depend for their 

 clearness on several highly variable factors, including : the strength 

 and other characters of the shore rocks ; the exposure of the coast 

 as it affects the fetch and power of the waves; the power of tidal 

 currents ; the position of wave-base at the old shore, especially the 

 depth of the rock-bench cut by the waves at the foot of a receding 

 sea-cliff; the degree to which the records of the higher stand of the 

 sea have been destroyed by the waves acting at present sea-level. 



The influence of rock variation is well illustrated in New England, 

 where glacial deposits Avere distinctly cliffed at the 20 ft. level, 

 while the massive granites suffered little benching. As already 

 stated, the contrast between the shores of the St. Lawrence and those 

 of Labrador in this respect is very striking. Even where the shore 

 materials were quite incoherent, as along young coastal plains, 

 sea-cliffing might not have taken place systematically at all. Modern 

 examples show prograding, rather than retrogression, of the shore- 

 line. Thus the sea-cliffs of the 20 ft. strand would vary in height 

 from zero upwards. 



The crest of a storm beach is not sea-level. The more powerful 

 the waves the greater is the difference of these two levels. From 

 published texts one can not always be sure that due allowance 



