W. M. Davis — The Great Barrier Reef of Australia, 343 



reefs may have bordered the Queensland coast not only during 

 its recent moderate submergence, but during a long antecedent 

 period of great downwarping, as a result of which the total 

 thickness of successive reef growths and of the lagoon deposits 

 behind them may be as much as one or several thousand feet. 

 The reasons for this interpretation are here set forth. 



Andrews was the first to apply modern physiographic methods 

 to the explanation of the coastal highlands of eastern Australia. 

 The region that he more particularly studied is locally known 

 as " JN^ew England," and lies in the northeastern part of New 

 South Wales, not far south of the southern end of the Great 

 Barrier reef which fronts the Queensland coast farther north. 

 The history of the highlands indicates the history of the off- 

 shore sea bottom or reef foundation also. Andrews' chief 

 results are that the N^ew England region, of complicated struc- 

 ture and once of mountainous form, as in block A, fig. 4, 

 was reduced to an extensive peneplain, FF^, in Cretaceous 

 time, and that as a result of successive broad uplifts of a north- 

 south belt, GGr^, MJ^, RK^, after shorter and shorter intervals 

 of time, three coastal peneplains of less and less extent, LL', 

 QQ, UIJ', have been eroded on the eastern slope of the uplifted 

 belt at lower and lower levels, so that they now form a series 

 of benches, each one a number of miles in breadth, separated 

 by irregularly dissected escarpments, K, O, S, independent of 

 rock structure, and from several hundred to a thousand feet in 

 height. The lowest and youngest of the peneplains, UU^, 

 now diminished in breadth, NN' ^ by subrecent submergence, 

 constitutes the present coastal lowland ; like the earlier pene- 

 plains it is often surmounted by monadnocks, large and small. 



Andrews gives only a brief discussion of the oif-shore changes 

 attendant upon the successive uplifts of the highland. His 

 most significant statements on this point are as follows : "Dur- 

 ing late Pliocene and Pleistocene times, a differential subsi- 

 dence took place for the coastal area . . . The formation of 

 the present Great Barrier reef probably does not antedate this 

 last movement of subsidence, although reefs doubtless existed 

 prior to the cycle of subsidence. ITnless the movements of 

 subsidence were accentuated in an easterly direction, the depres- 

 sion which determined the Barrier Peef must have been very 

 moderate in amount . . . The effect of the late subsidence 

 was ... to give birth to the Great Barrier reef."^ 



It is to the extension of this discussion, particularly with 

 regard to an eastward accentuation of subsidence, that the 

 present paper is directed. The successive uplifts of th'e coastal 

 region must have been of diminishing measure eastward : for 



^E. C. Andrews, An outline of the Tertiaiy history of New England. 

 Rec. Geol. Sarv. N. S. W., vii, 1903, 140-216 ; see pp. 2i4--215. 



