164 Scientific Intelligence. 



of America and Europe. Beneath the Cape System are found a 

 great thickness of closely folded and metamorphosed sedimentary 

 formations largely injected with granite and embracing as many 

 as four unconformable subdivisions. 



The base of the Cape System consists of the topographically 

 prominent Table Mountain sandstone, with a maximum thickness 

 of 5000 feet, remarkably constant in character over the whole 

 area of its present occurrence, probably over 90,000 square miles, 

 pointing to its deposition over a wide shallow platform with 

 unknown limits fronting a land which probably lay to the north- 

 ward. An interesting feature is the occurrence of a thick shale- 

 band with pebbles up to five inches in diameter occasionally 

 flattened and striated. The pebbles are scattered irregularly 

 through the shale and mud stone without any tendency to form 

 beds of conglomerate. Considering all the evidence, it is con- 

 cluded that the pebbles were distributed by floating ice some- 

 where early in Neopaleozoic times. 



Following the Cape System, conformably in the south but 

 unconformably in the northern portion of the Colony, is the 

 Karroo System, with a maximum thickness of not less than 14,000 

 feet; it is rich in the remains of Permo-Carboniferous and Triassic 

 reptiles. Its base, the Dwyka Conglomerate, a thousand feet in 

 thickness, appears to consist in the south of iceberg deposits and 

 in the north of true bowlder clay resting unconformably upon 

 striated and moutonneed surfaces with indications of ice move- 

 ment from the north toward the south. Several plates from pho- 

 tographs illustrative of these highly interesting occurrences are 

 given.* 



Sometime after the middle of the Karroo a period of folding- 

 set in, building the mountain structures of Cape Colony facing 

 outwards toward the oceans. This was followed by a period of 

 great basic intrusions and of volcanism closing the Triassic. 

 Since that time the history of Cape Colony has been preemi- 

 nently one of successive uplifts and erosion ; an erosion history 

 interrupted in early Cretaceous times by a partial subsidence and 

 probably an increased aridity of climate, and checked occasion- 

 ally in later times by an approach of the river valleys to base 

 level. 



It is to be noted that on the southeast the even coast line cuts 

 across the folded structures for a distance of four hundred miles, 

 and there are indications, as in a downfaulted remnant of the 

 Cretaceous, that post-Cretaceous faulting has played an important 

 part in this truncation of older structures and the present ter- 

 mination, at this place, of the continental platform. j. b. 



15. Tee Erosion Theory a Fallacy ; by H. L. Fairchild. 

 Bull. Geol. Soc. Amer., vol. xvi, pp. 13-74, pis. 12-23. Pub- 

 lished Feb., 1905. Read Jan. 1st and Dec. 30th, 1904.— In this 

 article the author defines glacial erosion as the power of making 

 vast and deep excavations in the solid or live rock, resulting in 



* See also the article on this subject by E. T. Mellor in this number, pp. 

 107-118. 



