31 



My remarks m this article will refer principally to the position 

 of the beds, to their relation to adjoining strata, and to the differ- 

 ence in geological age, which I conceive to exist between certain 

 portions of the shell deposits. As full a list of the Mollusca as 

 can be made out at present will be added, as necessary for the 

 illustration of the point last named. 



In its course towards the Wannon, the Grange Burn is joined 

 by two tributaries, viz.. Muddy Creek and Violet Creek. 

 Although all three are insignificant streams, and confined now in 

 narrow channels, yet the valleys through which they flow are not 

 only wide, but depressed considerably below the level of the sur- 

 rounding country. I have not observed any fossil outcrops in 

 the Violet Creek, which is the more remarkable, as they occur in 

 so many places in both the Grange Burn and Muddy Creek. 



It may be mentioned here that the term "Muddy Creek" beds^ 

 is used by common consent, as a convenient name for the whole 

 series of fossiliferous strata in this locality, and must be under- 

 stood, therefore, to include not only the deposits of Muddy Creek 

 itself, but also those of the Grange Burn, close at hand. 



The distance of Muddy Creek from the sea is about 40 miles,, 

 while the fossil-bearing strata (in the place marked "«" in the 

 map) are 385 feet above sea level. Mr. S. Mason's house on the 

 table-land overlooking the creek is 130 feet higher, or 515 feet 

 above sea level. This may be regarded as the general elevation 

 of the country in the neighbourhood, the slope to the sea-coast 

 being very gradual. These and the other levels given later on 

 are aneroid measurements of my own. The meteorological station 

 at Hamilton, about five miles distant, which is exactly 640 feet 

 above sea level, has been adopted as the starting point for the 

 observations made in the neighbourhood of Muddy Creek. In 

 other localities, either the sea itself, or some known elevation, has 

 formed a basis to work from. 



Going northwards from the Grange Burn, no outcrops of the 

 marine tertiaries occur in the whole of the county of Dundas, 

 except a small outlier towards its extreme western boundary, on 

 the margin of the River Glenelg. This region, lying between the 

 Grange Burn and the Wannon on the south, and the Glenelg on 

 the north, forms a plateau, occupied by palaeozoic, granitic, trap- 

 pean, and metamorphic rocks, and prolDably stood at too great an 

 elevation during tertiary times to be submerged. 



To the north and north-west of the Glenelg, however, the 

 marine beds again appear, and continue almost without interrup- 

 tion over a vast extent of country, the river in this part of its 

 course marking a well-defined geological boundary. 



By going along the Grange Burn to the westward, we soon 

 lose sight of the tertiaries, the mesozoic strata— which they, no- 



