462 PROCEEDINGS OF THE ALBANY MEETING 



The Society adjourned for luncheon. At 2.30 p m the Society recon- 

 vened, and the following paper was read : 



TUFF CONE AT DIAMOND HEAD, HAWAIIAN ISLANDS 

 BY 0. H. HITCHCOCK 



\_AhstracQ 



Since the pubHcation of the paper on the Geology of Oahu,* the author has had 

 an extensive correspondence with Doctor W. H. Dall and Doctor S. E. Bishop, of 

 Honolulu, respecting the origin of this cone. The first thinks that coralline beds 

 are interstratified with the tuff, implying several periods of eruption, between 

 which the sea encroached on the land. The second insists that there was only 

 one brief eruption of the tuff which produced the cone with coralline fragments 

 included, after which eolian beds accumulated on the southern side. Both of those 

 views were briefly stated. Doctor Bishop's paper, with an excellent topographic 

 map of the cone, is printed in full in the American Geologist.! 



The following paper was then read : 



HYPOTHESIS TO ACCOUNT FOR THE EXTRA-GLACIAL ABANDONED VALLEYS OF 



THE OHIO BASIN 



BY M. R. CAMPBULl. 



lAbstracf] 



The lower courses of the Allegheny, Monongahela, Kanawha, Guyandot, Big 

 Sandy, and Kentucky rivers are characterized by abandoned channels, which 

 generally range from 100 to 200 feet above the present streams. Generally these 

 channels are deeply covered with silt, but sometimes the rock floor is only par- 

 tially obscured by a thin layer of sand and gravel. The streams which have 

 forsaken these valleys have sought new routes, along which they have carved deep 

 channels through the upland topography. Teay valley, in West Virginia, is per- 

 haps the most noted example, but the old (thannels atCarmichael and Masontown, 

 on the Monongahela river, and opposite Parker, on the Allegheny river, are also 

 well known. 



No reason has been assigned for the abandonment of these channels; they can 

 not be considered as "ox-bows," and they are all beyond the limit of glacial ice. 

 The present hypothesis seeks to explain them through the breaking up of river 

 ice and the formation of local ice-dams which were of suflicient height to force the 

 water over the lowest divide in the rim of the basin and which persisted long 

 enough for the stream to intrench itself in its new position. 



The paper was discussed by I. C. White, W. M. Davis, G. K. Gilbert, and 



* Bull. Geol. Soc. Am., vol. xi, pp. 15-60. 



t Amer. Geologist, vol. xxvii, January, 1901, pp. 1-5. 



