ABSTRACTS OF PAPERS 77 



ing valleys. At the mouths of the hanging valleys projections occur into the 

 main valleys or into the lake. These projections are here given the name of 

 "hemicones." The purpose of this paper was to illu.strate these hemicones 

 and to briefly consider their origin. 



Read in full from manuscript. 



BLOCK DIAGRAMS OF STATE PHYSIOGRAPHY 

 BY A. K. LOBECK ' 



(Al)stract) 



The broader physiographic features of a state, or a large i)ortion of a state, 

 may best be portrayed by means of a block diagram which shows the relation 

 of surface form to underground structure. The possibilities of this use of the 

 block diagram method were illustrated by several .specimen di-awings. 



Eead by title, drawings being on view in exhibition room, 



KILAVEA, A DROP-FAULT CRATER 

 BY GEORGE CARROLL CURTIS ^ 



{Abstract) 



On withdrawal of molten lava in the active pit of Halemaumau, support to 

 the adjacent walls of frozen lava is lost and blocks of it subside, taking a 

 form roughly concentric with that of the liquid lake. Such down-faulted 

 masses are common within the eruption pit, its rim being stepped with series 

 of corresponding lesser faults and cracks. The great caldera (Dutton) rim, 

 of some 9 miles in circumference, 3 in diameter, and reaching nearly 300 feet 

 in height, surrounds a floor or sink which appears to represent the "black 

 ledges" or flow levels in the present pit of eruption, and large down-faulted 

 blocks lie like giant steps along its extensive scarp. 



Outside the main rim, interrupting the gentle slopes of the Kilauea cone, 

 are other escarpments which appear of similar origin, one at half a mile and 

 another at about a mile distant being the highest. The broad saddle between 

 Kilauea and Kilauea Iki is a comparatively large dropped fault block, and 

 a similar series of blocks and fissures occur in the several dormant surround- 

 ing crater pits. Kilauea is perhaps the best example of the drop-fault volcanic 

 crater. 



Presented by title in the absence of the author. 



1 Introduced by Richard I£. Hice. 

 ^ Introduced by E. O. Hovey. 



