MR. E. W. BINNEY ON A DOLERITE AT GLEASTON. 89 



III. Description of a Dolerite at Gleaston, in Low Furness. 

 By E. W. BiNNEY, F.R.S., F.G.S. 



Read March 31st, 1868. 



During the last 30 years the tract of land known as the 

 Hundred of Low Furness has been investigated and de- 

 scribed by several geologists. It was one of the earliest 

 fields investigated by the venerable Sedgwick, who has left 

 us a most valuable memoir of his labours in that district. 

 Since then, Mr. Jopling, myself, and Sir R. I. Murchison 

 and Professor Harkness have published descriptions of the 

 Silurian mountain -limestone andPermian formations of the 

 country. Miss E. Hodgson has also given us information 

 as to the drift-deposits overlying the palaeozoic strata. 

 Still, notwithstanding what has been done, it may confi- 

 dently be asserted that the peninsula comprising the 

 southern part of the Hundred of Low Furness has yet to 

 be carefully examined before its geology can be said to be 

 thoroughly known. 



None of the above-named persons appear to have been 

 aware of the occurrence of any trap-dykes in that district, 

 judging from their published writings, with the exception 

 of Mr. Jopling, who, in his sketch of the geology of Low 

 Furness and Cartmel, comprehending the Hundred of 

 Lonsdale north of the sands, published in 1843, when 

 speaking of the geology of Gleaston, says : — '^ Carbonifer- 

 ous limestone abounds, and in the quarries near the castle 

 are many fossils beautifully preserved in the shale-beds 

 between those of the limestone ; there is also a vein of 

 trap.^^ At page 72, the same author says, "There are 

 also appearances of trap near Gleaston, associated with 

 limestone breccia. ^^ 



In the month of October last, Miss E. Hodgson was so 



