226 NOTE ON THE SOUTH DTJEHAM SALT BOEINGS. 



the cores as are left there. All the Carhoniferous cores had 

 been removed for safety, and the Triassic cores had fallen to 

 pieces, and are fast being reduced to dust. In a core of very 

 fine, white, compact limestone I found a few small specimens of 

 Productus horridus, which is a very characteristic fossil of our 

 Lower and Middle limestone series. One of the specimens 

 shews the hinge line with its row of long spines, and associated 

 with these was a specimen olAxinus dubius, Schloth., of medium 

 size, and part of an unknown organism which I have not been 

 able to identify or to determine its affinity. These fossils evi- 

 dently belong to the Lower-limestone series. The only stratum 

 I can call to mind like this is a thick bed formerly worked near 

 Hartley's Glass "Works, Deptford, near Bishop wearmouth,- out of 

 which Mr. Jas. Kirkby procured some very similar specimens of 

 Productus. This low-seated bed of limestone from the bore-hole 

 is, however, much denser and more crystalline, and also contains 

 small globular deposits of Gypsum or Anhydrite. 



Most geologists will, no doubt, be inclined to conclude from a 

 comparison of the beds in the sections quoted above that the 

 Upper-limestones found in the Salt borings on the Tees are 

 identical with the Yorkshire Brotherton beds, and also with the 

 Plattendolomit of Germany. And as the three fossils found in 

 the Plattendolomit are species identical with those found in the 

 Brotherton beds and also in the limestone-cores of one of the 

 Teesside borings, and as these fossils are well-known Upper 

 Magnesian-limestone species, it seems safe enough to conclude 

 that these Upper beds of limestone, with the Rock Salt below 

 them, are of undoubted Permian age ; at least this was the con- 

 clusion I came to after a first examination of the Saltholme trial 

 boring. 



