Geological Structure about Mornington. 33 



Two years later Selwyn (2) published a much fuller report on 

 the district, accompanied by a map on the same scale, but 

 showing greater detail. The section is instructive, but does not 

 touch the area under consideration. It extends from near 

 Somerton to Mount Corhanwarabul (Mount Observatory), and 

 the distance of thirty miles was chained, levelled and drawn to 

 true horizontal and vertical scale, the scale being six inches to a 

 mile. In dealing with the tertiaries twenty-two genera of 

 mollusca are mentioned as occurring in the Mornington clays. 



These old reports of Selwyn's, buried as they are in a mass of 

 Parliamentary papers, are not often referred to, but contain a 

 large amount of interesting information. Subsequent explora- 

 tions have somewhat modified, as is natural, a few of his 

 conclusions, but they still form a safe basis on which we can 

 build, and show how soon he gained a clear insight into the 

 geological structure of Victoria. 



Shortly after this. Dr. Selwyn (3) presented a suite of fossils 

 from INIornington to the Royal Society of Tasmania, and the 

 collection is described as showing a close resemblance to forms 

 found at Table Cape. 



In 1857 Sir F. M'Coy (4), in his evidence before the Coal 

 Commission, alludes to the small area of " carboniferous deposit " 

 near Schnapper Point, and says that all that area between the 

 granite and the sea was found to be traversed at a little depth 

 by a " sort of dyke " of igneous rock or trap, similar to that 

 which occurs in the Cape Patterson beds on the coast, and 

 similar to that found at a depth of nearly 200ft. in the two more 

 northern borings. Dr. Selwyn, in his evidence before the same 

 commission, said, in reference to Schnapper Point and the shores 

 of Port Phillip Bay, " In this district 200ft. of coal strata have 

 been bored through, and in that thickness no seam more than 

 3 inches thick has been discovered. If any available coal deposit 

 exists in this neighborhood, it can only be under the waters of 

 Port Phillip. Inland the coal strata are most undoubtedly and 

 completely cut off by being faulted against older rock. This 

 line of fault extends in a direct line from Frankston to Arthur's 

 Seat, parallel to the coast ; beyond the latter point, the coal rocks, 

 if existing, are overlaid by such a thickness of newer tertiary 

 deposits as to render them of no practical value." 



3 



