NA TURE 



21 7 



THURSDAY, JULY 6, 1S93. 



THE CREA T BARRIER REEF OF A USTRALIA. 



The Great Barrier Reef of Australia ; its Products and 



Potentialities. By W. Saville-Kent, F.L.S,, F.Z.S., 



F.I.Inst. 387 pp., 64 pis. (London : W. H. Allen 



I and Co.,. Limited.) 



T^HE first thought that strikes one in glancing through 

 i- this magnificently illustrated volume is the dili- 

 ;ence and skill of the author in photography and the 

 nterprise of the publisher. Never before has a semi- 

 cientific work been illustrated with such a wealth of 

 lates. The illustrations will go far towards giving a 

 ealistic impression of some of the beauties of coral seas 

 the untravelled, and will awaken many recollections 

 f happy hours of exciting shore collecting in those who 

 ave waded on coral reefs and peered over a boat-side at 

 be edge of a reef. 

 The objects of the author in writing this book are set 

 own in the Preface as being manifold — primarily to 

 ilace before the reading public generally, and the 

 cientific world in particular, more extensive and accurate 

 formation about coral-reefs as represented by the 

 Tgest existing coral structure. Another prominent 

 lurpose is to lead to the industrial development of the 

 marvellous resources " of the Great Barrier Reef. 

 The book commences with a detailed description 

 over forty photographs, of reefs and corals. These 

 ill well repay careful study, and to some naturalists they 

 11 be the most valuable portion of the work. The 

 lustrations are unique for beauty, truthfulness, and 

 umber, and the descriptions are short and to the point. 

 wo photographic plates and three sketches illustrate 

 me groups of corals on the reef at Vivien Point, 

 hursday Island, of which measurements are given to 

 rnish some data concerning the average rate of growth 

 f the more important reef-forming species. The 

 umerous plates of reef-scapes may possibly give the 

 npression that coral reefs always present such scenes 

 f interest and beauty, but the reader must be warned 

 at it is only at low spring tides that he will see reefs 

 s here photographed. At ordinary low tide the exposed 

 rface of a reef is ugly and comparatively uninteresting. 

 he amount of exposure to the fierce rays of a tropical 

 in which some corals can withstand will be surprising to 

 ,any zoologists. In a few cases a future zoologist will 

 J able to compare the ad interim growth or modification 

 f a reef by the landmarks which appear in certain of 

 ir. Saville- Kent's photographs; but, unfortunately, little 

 iformation of this kind is given, and it is still more to be 

 Sgretted that the aspect of the area photographed is -not 

 tcorded, there being no indication whether it is on the 

 de of the steady south-east trade-wind or subject to 

 le calms and storms of the north-west monsoon. It 

 ■fluid further bje of great interest if one knew why one 

 sef or portion of a reef consisted almost solely of the 

 «ius Madrepora, while Porites characterises another 

 rea, or mixed corals a third. 



/of origin. This consists largely of appropriate quotations 

 from other writers. 



The third chapter is devoted " to a consideration of 

 the general structure and most probable mode of origin 

 of I he Great Barrier Reef of Australia," the more 

 notable features of the reef being described in order, 

 beginning with the most southerly end. The view is 

 enunciated " that coral-reefs are produced in the tropics, 

 not with relation so much to the intrinsic reef-con- 

 structing properties of the specific coral polyps, but with 

 relation to the rule that reef consolidation (or the 

 amalgamation of coral debris into a more or less solid, 

 coarse or fine, concrete, or into a finer-grained, compact 

 limestone) is associated only with the rapid evaporation 

 of the lime-saturated sea-watfr on inter-tropical, tidally 

 exposed, coral banks or beaches." The presence of dead 

 specimens of reef corals in Moreton Bay suggests two 

 questions. Why did they not form reefs or reef-rock 

 when they were abundant ? and why have they now all 

 but become extinct? Mr. Saville-Kent answers the first 

 question by suggesting that the temperature of Moreton 

 Bay is insufficient to produce the requisite rapid evapora- 

 tion, and the second by pointing out that the increasing 

 size of the three large islands which hem in the bay has 

 latterly tended to freshen the bay in flood time, and this 

 has led to the destruction of the corals. In his description 

 of the Qreat Barrier Reef Mr. Saville-Kent has quoted 

 largely from Jukes' "Voyage of the Fly" and thus 

 endorses the accuracy of the observations of that dis- 

 tinguished naturalist. With regard to the question of 

 subsidence and elevation, Mr. Saville- Kent found at many 

 stations throughout the Barrier region (notably at Albany 

 Pass, Cape York) large expanses of dead brittle coral 

 in situ beWveen high-water mark and the living banks. 

 These beds of dead coral are now exposed to atmospheric 

 influences which are antagonistic to coral growth witlf 

 every ordinary springtide, and hence he concludes the 

 general upheaval of the area on which it grew ; additional 

 evidence is given from the shallowing of a bay in 

 Magnetic Island, near Townsville. 



"It is difficult," Mr. Saville-Kent adds, " to associate 



the phenomena described in the foregoing record with 



any other than a movement of upheaval ; but, accepting 



this as proven, and premising for the nonce that the 



whole length and breadth of the Barrier region exhibited' 



a similar testimony of emergence, the amount raised, a 



foot or two only, would be as nothing compared with 



the latitude of movement in one direction or the oHher 



that is required to account for the construction of the 



Barrier's mass. Had the Great Barrier been fashioned 



during a prolonged epoch of upheaval, substantial 



evidence of such movement would be yielded by the strata 



\ of the seaboard which it skirts ; but of this there is 



virtually none." Thus Mr. Saville-Kent supports the 



conclusion arrived at by Prof Jukes and by the 



Reviewer that this is not an area of recent elevatioil] 



Mr. Saville-Kent refers to the well-known fact that ill of ' 



the few big breaches in the Barrier's outer rampart are 



opposite large estuaries, though at the present time too 



remote from them to be influenced by their streams. 



These are to be expected on the subsidence hypothesis. 



Mr. Saville-Kent further'elaborates an argument for this 



m 



The general reader is provided with the indispensable _ _ ..^ 



ccount of coral reefp, their general structure and theories , theory on the fauna of Tasmania and NSw^Guinea being 

 NO. I 236, VOL. 48] ' L 



