124 PROCEEDINGS OF THE AMHERST MEETING 



by the Lower Cambrian overlap. Later deformation seems to have taken 

 place in the Middle Cambrian and to have been followed by an Upper Cam- 

 brian (Saratogan) overlap. The principal deformation is of the usual Appa- 

 lachian kind. 



Presented in full extemporaneously. 



Discussed by C. E. Gordon, with reply by the author. 



Discussion 



Professor Gordon : I was very much interested in Mr. Keith's paper. My 

 own studies in Vermont geology have carried me into the northwestern part 

 of the State, where I have observed and traced, throughout their extent, the 

 boundaries of the great thrust displacements which are depicted on Mr. 

 Keith's map. After recognition of the general age relations of the rocks in- 

 volved, these great thrust displacements are hardly less clearly visible in the 

 field than when they appear as shown on the map. The speaker's studies 

 were first begun in the southwestern and central western parts of the State, 

 where thrust displacements were clearly recognized and described : but, if 

 possible, the field relations are more involved at the south than along the 

 northeastern border of Lake Champlain. 



I wish especially to note that during the season of 1021, in addition to 

 Lower Cambrian and Ordovician fossils found at various places in north- 

 western Vermont, I found two forms in certain slates in the gorge of the 

 Missisquoi River at Highgate Falls which I identified as Staurograpt-us 

 dichotemus Emmons and a fragment of Dictyonema sp., possibly flabelliforme. 

 I submitted these specimens to Dr. Ruedemann, of Albany, who thought the 

 supposed Staurograpt-us to be a young Dictyonema flattened in the direction 

 of the vertical axis, and that the Dictyonema might be a member of the 

 flabelliforme group, but also comparable with I), rectioineatum. He felt con- 

 fident that the forms, in the absence of exact specific determination, belonged 

 either to the Schaghticoke (Upper Cambrian) or the Deep Kill (Beekman- 

 town) shale horizons as known in the Hudson Valley. 



RECONNAISSANCE OF THE EASTERN ANDES BETWEEN COCHABAMBA AXD 



SANTA CRUZ, BOLIVIA 



BY KENNETH C. HEALD AND KIRTLEY P. MATHER 



{Abstract) 



This region was seen by the authors in December, 1919, during the progress 

 of geological exploration for Richmond Levering and Co., through whose 

 courtesy this paper is available. 



The region is one of rugged relief. The dissection ranges from youthful to 

 mature, increasing in intensity from west to east. The controlling drainage 

 was developed on a peneplain, probably of late Tertiary age, small remnants 

 of which remain. This peneplain sloped eastward from an elevation of a 

 little more than 13,000 feet in the vicinity of Cochabamba and Arani to an 

 elevation of about 3,000 feet in the easternmost ridge of the Sierra de Santa 

 Cruz. 



