82 Reviews — Dr. John Ball — 



which it closely resembles. This point is one of great interest on 

 account of the discussion which has taken place as to the age of the 

 Nubian Sandstone. In the region we are considering the vast period 

 of time separating the Carboniferous Limestone from the marine 

 Cenomauian clays is represented by 650 metres of sandstone, which 

 are conformable to the rocks below and above, and in which no break 

 can be detected. Dr. Ball separates the lower portion of this series 

 (130) under the name of Upper Carboniferous Sandstone, on account 

 of the occurrence of fossils of the Lepidodendron type, from the upper 

 portion (500) to which he restricts the name of Nubian Sandstone. 

 The only traces of fossils found in the upper portion are a piece of 

 silicified wood " similar to that which occurs in the Nubian Sandstone 

 of Egypt", and a thin layer of very impure coal. Owing to the 

 discovery of Inoceramus in the Nubian Sandstone of Aswan and the 

 intercalation of the sandstone with the overlying marine Cretaceous 

 in other parts of Egypt this formation is now generally regarded as 

 being of Cretaceous age. Until quite recently no trace of marine 

 fossils of Triassic or Jurassic age has been found either in Egypt or 

 Sinai, but Dr. Ball refers to a discovery of Jurassic deposits in the 

 northern portion of the peninsula, and suggests that part of the 

 Nubian Sandstone may be of the same age. Details of this important 

 discovery do not appear to have been made public. 



So far we have been referring to about three-fourths of the area 

 covered by the map. This portion is bounded on the west by a series 

 of important faults following a general direction a little east of 

 south, roughly parallel to and at an average distance of about ten 

 kilometres from the Gulf of Suez. The remaining portion consists 

 principally of Campanian strata, but contains also representatives of 

 the Eocene and Miocene periods. At one point Miocene rocks are 

 faulted against the Lower Carboniferous Sandstone, and the throw is 

 estimated at probably not much less than 2,000 metres. The 

 faulting is regarded by the author as belonging to the close of the 

 Miocene period ; but the possibility of its having commenced at an 

 earlier period must not be overlooked. 



Campanian strata (300?) form a highly dissected hilly country of 

 a dazzling white aspect. Eocene strata appear to rest conformably 

 on the Campanian. They are much thinner than those on the 

 opposite side of the Gulf of Suez and in the Nile Valley. The 

 Miocene rocks occur in detached patches and comprise conglomerates, 

 gritty limestones, clays, and chalky rocks often impossible to 

 distinguish from Eocene or Cretaceous in the absence of fossils. The 

 author sums up his observations on the Miocene deposits in this part 

 of Sinai by saying that " the more easterly portions are characterized 

 by great accumulations of conglomerates and grits, indicating that 

 the old shore ran approximately along the line of the great fault 

 already referred to, while farther to the west there is increasing 

 predominance of limestones, clays, marls, and gypsum, indicating 

 deeper water conditions for certain beds ". 



The geological history of Egypt during post-Eocene times is of 

 great interest, but it is difficult to correlate the available information. 

 The prolonged hydrocratic movement which lasted during the 



