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The "Bay of Biscay" Soil 



OF SOUTH AUSTRALIA, AND ITS FORMATION. 



By Otto Teppek, F.L.S., Corr. Member. 

 [Read June 1, 1880.] 



INTRODUCTORY CITATION. 



" I may remark in connection with the clays overlying the Miocene lime- 

 stone that it is on their surfaces that the ' Bay of Biscay' land prevails. 

 This name is applied to tracts covered with mounds or ridges grouped in the 

 mast irregular way, and without any relation to the natural slope of the 

 surface. The ridges, which rarely exceed a foot in height, are composed of 

 clay, while the depressions are occupied by alluvium or sandy loam ; and 

 though it is generally held that the soil of the depressions extend in depth, 

 yet my observations are totally opposed to that view. How the depressions 

 have been formed on tbe clay soil, and how they have been partially filled, 

 are questions which, I hope, will occupy the attention of some member of 

 this Society." — Prof. B. Tate, F.G-.S. ; President's Anniversary Address 

 Trans. A. Phil. Soc, 1878-9, page lx. 



In many parts of South Australia a clayey soil occurs, which, 

 is popularly called by the above name, and is justly regarded 

 by most people as one of the most productive. Among other 

 localities we meet it in the undulating Tertiary regions north of 

 Grawler, in the neighbourhood of Tanunda, Greenock, Sheaoak 

 Log, Freeling (villages north of Adelaide), and extending far 

 beyond Kapunda. Again, the same soil is found in small 

 patches near Ardrossan, Yorke's Peninsula. Maitland, in the 

 centre of the same peninsula, is surrounded by it, from whence 

 it stretches into the neighbouring hundreds. In fact, it is 

 found to a greater or less extent in many counties, but the 

 above localities have been examined by me. 



Its most characteristic feature is the unevenness of its sur- 

 face, forming shallow round depressions 6 to 18 inches in 

 depth, and without an outlet. These arc surrounded by eleva- 

 tions of varying width, sometimes forming almost ridges, at 

 others equalling or exceeding the depressions in area. The 

 sides are never steep ; but frequently one incline is longer than 

 the other, then the shorter one is also the steeper. We meet 

 this surface formation on the broad gently-rounded summit of 

 hills, as well as on almost level gradually rising plains, bounded 



