PROFf:ssof; /. a DAN.rs Ri'r pence. 



91 



rather too rapidly to allow its corals to extend across the trench thus t'ormed and cfl'ect a union wuli the 

 main mass. Of course, if a fissure-like hollow were once established between two masses of growing coral in a 

 subsiding area, it would not be readily filled up, unless the edge of its outer wall were sufficiently near the surface 

 to suffer much from the violence of the waves. 



"The former section seems to me to be inexplicable under the conditions ordinarily admitted for coral growth, unless 

 we suppose that the bottom of the lower ditch, now at a depth of over 1200 feet (200 fathoms), was formerly situated 

 within about twenty-five fathoms of the surface ; so that a subsidence of more than 1000 feet may fairly be claimed for the 

 coral reef of Masamarhu." 



As a final extract from the testimony in favour of the subsidence theory, adduced in Professor 

 Bonney's "Appendix," already so extensively quoted, we reproduce the highly interesting results 



No II 



Oryloi^ 



Island 



Sketch 01 Mas«m»rhu 1 

 Shot¥/n^ approximate 

 position of Sections 



Lur is'SOV Lite 3S'45 £ 



I Set Mile 



, q C*6lfi 



of some deep borings recently carried out near Honolulu, the chief town of Oahu, in the Sandwich 

 Islands. The data here submitted were originally contributed by Professor Dana to the American 

 Journal of Science, Vol. XXXVII., i88g. They indicate be3'ond question a very considerable 

 amount of subsidence in the region referred to, the depth at which the " hard coral-rock," or reef- 

 conglomerate, runs, being in all instances considerably below the plane at which it could have 

 been originally formed. 



The details of the composition of the strata perforated, given in Professor Dana's report, are 

 as follow : — 



N 2 



