396 Geological Society. 



Izalco, in the Republic of Salvador, which has been in active 

 eruption for over one hundred years, suddenly ceased to be so 

 within a fortnight of the period at which the communication was 

 sent (Dec. 20th, 1896), and he notes the occurrence of seven shocks 

 of earthquake in England on December 17th, 1896. He quotes 

 remarks concerning the volcano, which were contributed by him to 

 the .' North American Review ' in January 1S96. 



2. ' The Red Rocks near Bonmahon on the Coast of Co. Water- 

 ford.' By F. R. C. Reed, Esq., M.A., E.G.S. 



The rocks which are considered in this paper have been regarded 

 by some authorities as deposits interstratified . with the Lower 

 Palaeozoic rocks of the district, while others have maintained that 

 they are of Old Red Sandstone age. Tt is the object of the author 

 to show the correctness of the latter supposition, and he brings 

 forward evidence to prove that the red rocks rest unconformably 

 upon the Lower Palaeozoic rocks, or are faulted against them, and 

 that the breccias of the red rocks contain fragments of the Lower 

 Palaeozoic rocks, and also of intrusive rocks which break through 

 the latter. The red rocks also resemble deposits which are known 

 to be of Old Red Sandstone age. 



The Old Red Sandstone rocks of the district form an irregular 

 and incomplete elliptical ring around a denuded plateau of older 

 rocks. The incompleteness is due to the concealment of the southern 

 part of the ring beneath the sea ; but if the southern part of this 

 ring be as irregular as the northern portion, faulted patches of the 

 Old Red Sandstone rocks may well come in among the older rocks of 

 the cliffs in the positions where the beds which are discussed in this 

 paper occur. 



3. ' On the Depth of the Source of Lava/ By J. Logan Lobley, 

 Esq., E.G.S. 



The author contends that lava cannot have been brought to the 

 surface from a depth of 30 miles, as fissures which would serve 

 as conduits could not exist at that depth, and, moreover, the lava 

 would be consolidated before it reached the surface, owing to 

 contact with cool rock for a considerable period. He argues that 

 the pressure of the overlying rocks would cause the rocks even at a 

 depth of 10 miles to be practically plastic, as shown by M. Tresca's 

 experiments, and that no continuous fissure could occur in such 

 rocks. Estimates of the volumes of ascending lava-columns were 

 given, with a diagram comparing them with a 30-mile thickness of 

 rocks, 



