TITLES AND ABSTRACTS OF PAPERS 33 



Discussion 



Prof. William H. Hobbs : A recent visit to the locality at Aci Reale, in Sicily, 

 where pillow lava is exposed, enables me to say that the pillow structures are 

 strikingly like those shown in some of Professor Lewis's pictures. The late 

 Dr. Tempest Anderson has described watching the formation of pillow lava 

 where the lava stream from the eruption of Matacanu in 1906 was discharged 

 into the sea. There is, I believe, a general acceptance of the view that the 

 ellipsoidal basic rocks of the Lake Superior province were extruded into water. 



Prof. J. P. Iddings : W. L. Green has described the flow of lava from the 

 eruption of 1859 on Hawaii over a low shelf into the sea. It came from under 

 the crust in flattened spheroidal masses which fell into the water and must 

 have produced an aggregation with the structure of so-called "pillow" lava. 



Prof. A. P. Coleman suggested that pillow structure was really due to rapid 

 cooling, perhaps not necessarily under water. 



The Society adjourned about 12.45 o'clock, and reconvened in three 

 sections at 2.30 o'clock. 



TITLES AND ABSTRACTS OF PAPERS PRESENTED BEFORE THE FIRST SECTION 

 AND DISCUSSIONS THEREON 



The first section met, with Vice-President E. D. Salisbury as presiding 

 officer and E. 0. Hovey as Secretary, and took up the papers entered in 

 the printed program under G-roup A: Dynamic, Structural, G-lacial, 

 Physiographic. 



EARTHQUAKE SEA WAVES 

 BY HARRY FIELDING REID 



(Abstract) 



The explanations so far offered of the origin of great waves set up by sub- 

 marine earthquakes are unsatisfactory, among other reasons, because they do 

 not explain why the waves first appear as a depression of the water at some 

 ports and as an elevation at others. The elastic rebound theory offers a 

 satisfactory explanation of these facts. The accounts of some great submarine 

 earthquakes and the records of tide gauges were examined and shown to 

 support the theory. 



Presented in abstract without notes. 



Discussion 



Prof. William H. Hobbs : It is not clear to me in what respect Professor 

 Reid's theory of tsunamis accords better with the facts of observation than 

 that which assumes the sinking of a section of the ocean floor with occasional 

 uplift of a neighboring block on either side. Although the arrival of a 

 positive wave in advance of a negative at some shore stations appears to have 

 III — Bull. Geol. Soc. Am,, Vol. 25, 1913 



