34 PROCEEDINGS OF MADISON MEETING. 



2. Evidence of extensive erosion in this region during the interval between the 

 Cretaceous and Eocene deposition has not yet been found to be conclusive, but in 

 the coastal plain region further seaward such evidence does exist. 



3. If extensive Miocene beds ever existed in this region they were removed be- 

 fore the time of the Lafayette deposition. 



4. There are unmistakable evidences of two periods of extensive erosion : (a) One 

 post-Eocene and possibly post-Miocene, but pre-Lafayette ; (6) the other post- 

 Lafayette but pre-Columbia. During the first of these practically all of the Miocene 

 formation (if it ever existed in this region), nearly all of the Eocene, and a large 

 part of the Cretaceous formation was removed from the Sand-hill country. During 

 the second of these erosion intervals there was removed fully one-half of the 

 Lafayette formation and additional portions of the formations underlying. There 

 are evidences of limited post-Columbia erosion, but the amount is insignificant as 

 compared with the work of the two erosion intervals just mentioned. 



5. The extent of the submergence of this region during these succeeding periods 

 of deposition can be made out approximately. Between the Cape Fear and Peedee 

 rivers the position of the land during the later Cretaceous deposition could not 

 have been less than 600 feet, and was probably not greater than 800 feet. The 

 Eocene remnants capping the hills at an elevation of 500 feet above tide represent 

 older Eocene deposits. The submergence during Eocene deposition could hardly 

 have been less than 600 or 700 feet and may have been several hundred feet more, 

 and the Eocene waters for a short time may have covered a considerable part of 

 the Piedmont plateau and washed against the slopes of King's and Anderson's 

 and the Sauratown mountains. Six or seven hundred feet may be stated as a 

 probable maximum submergence during the deposition periods of the Lafayette 

 and Columbia. 



6. Observations have been made which will aid in determining approximately 

 the amount of elevation of the land during the several erosion intervals, but they 

 are not complete enough to warrant their discussion within the limits of this paper. 



7. In conclusion, it may be stated that the general topography of the Sand-hill 

 country is as old as the post-Cretaceous and post-Eocene erosion intervals. The 

 valleys and stream channels formed at that time were subsequently filled or nearly 

 so during the Lafayette deposition, but they were opened up again along the same 

 general lines during the post-Lafayette erosion interval. This was followed in 

 turn by the comparatively brief Columbia submergence, during which was laid 

 down the thin covering of sand in the region under consideration, and of finer 

 sand and loam and clay further seaward. These materials again filled the stream- 

 channels and adjacent low, level valleys, and they are again being removed by 

 post-Columbia erosion ; but these recent changes have left the general topography 

 much the same as it was long before. 



In discussing the paper W J McGee said : 



To one who is familiar with the difficulties attending field-work in the Coastal 

 plain, the results of Professor Holmes' studies seem especially important. His 

 contributions to the structural geology and the genetic history of this region have 

 been so clearly stated as to leave no room for criticism and little room for remarks 

 save in commendation. I beg, however, to direct special attention to the clear- 

 ness and fullness with which he has elaborated that part of the region which was 

 previously most obscure, i. e., the later portion, represented by the vaguely defined 



