Reviews — Some Mineral Oil Regions. 427 



II. — Some Mineral Oil Regions. 



1. Eepoet on Petroleum in Papua. By Arthur Wade, D.Sc. — 

 The author is to be congratulated on having brought to notice a part 

 of the Empire in which the oil indications are certainly widespread, 

 though it remains for actual drilling to test the real productiveness 

 of the field. The oil indications are noted in a series of sandstones 

 and mudstones of Middle Tertiary age, and are folded in a general 

 north-south direction. These beds are partly overlain by a calcareous 

 succession of Upper Tertiary age, which has east-west trend lines 

 parallel to the coast. It appears probable that the east-west trend 

 lines of Java extend into Papua, and in the latter country they 

 begin to swing round into the north-south trend lines which the author 

 describes; this inference appears to be confirmed by the inconstancy 

 of the trend lines in certain areas. 



The hypothesis that the minor crumpling of the anticlines is due 

 to the falling in of the crests is interesting and important in its 

 technical application to oil drilling, but it certainly demands more 

 proof than has been given in the paper. 



2. The Moorcroft Oil-field and the Big Muddy Dome, 

 Wyoming. By V. H. Barnett. (Bull. 581 C, U.S. Geol. Surv.)— 

 Both these areas are composed mainly of Cretaceous rocks, the 

 Montana and Colorado groups being well developed. Doubtful 

 Jurassic beds also occur, while in Big Muddy Dome, Tertiary 

 sandstones and shales occur in small patches. The general lithology 

 and structure are similar to those of neighbouring oil-fields along the 

 eastern border of the Pocky Mountains, but the commercial prospects 

 are distinctly poor. In the Moorcroft region, a poor oil-bearing sand 

 is noted, but the structure is unfavourable for subterranean storage, 

 whilst in Big Muddy Dome it is significant that the only horizon 

 which the author claims may contain oil in the middle of the dome, 

 i.e. the Wall Creek Sandstone, has nowhere along its outcrop been 

 proved to contain any bituminous matter. 



3. Oil- and Gas-fields in Wayne and McCreary Counties, 

 Kentucky. By M. J. Munn. (Bull. 579, U.S. Geol. Surv.)— The 

 structure of this region is that typical of Pennsylvanian oil-fields, 

 consisting of gently undulating strata ranging in age from the 

 Ordovician to the Carboniferous. The latter is represented by a good 

 development of both the Pennsylvanian and Mississippian sub- 

 divisions with the usual unconformable relationship, the Mississippian 

 consisting mainly of limestones and containing the oil-bearing strata. 

 The Chattanooga Shale at the base of the Carboniferous is correlated 

 with the Devonian, though the evidence is unsatisfactory. Below 

 these shales is a marked break in the succession almost eliminating 

 the whole of the Silurian, whilst the Ordovician are not exposed but 

 are found in boreholes. 



With regard to the distribution of the oil pools, it is remarkable 

 that these appear to occur in the sides of the gentle synclinal sags. 

 This peculiar distribution may be the result of unequal porosity in the 

 oil-bearing bed, and also the result of gas pressure in a water-free 

 horizon. 



