294 T. Y. HOLMES ON THE PERMIAN, TRIASSIC, AND 



from 15 to 20 feet deep, or perhaps half the average thickness of the 

 Glacial drift. Indeed a well-sinker, living near the southern border 

 of the Lias*, informed me, mistaking the motive of my inquiry, 

 that I need not be afraid of meeting with any rock below the drift 

 in the locality around his home, as he had sunk at various places he 

 mentioned to depths of 20, 30, or 40 feet without penetrating any 

 thing but sand, gravel, or clay ; for instances in which water, 

 attained on reaching a clayey stratum of drift, has been lost on 

 touching porous sandstone below, have made well- sinkers very care- 

 ful not to go a single foot lower than is absolutely necessary in the 

 case of ordinary dwellings. 



The Lias area has, during the last 250 years, been much explored 

 in search of evidence of coal. It will not seem strange that such 

 has been the case, when it is remembered that the dark shale form- 

 ing so large a proportion of the rock visible would naturally seem 

 identical with the dark shale of the Coal-measures, and a striking 

 contrast to the red Permian and Triassic beds around. The non- 

 Carboniferous, and probably Liassic, nature of the formation was 

 first discovered by Mr. E. B. Brockbankf, who, on finding Ammo- 

 nites and other fossils in Thornby Brook, sent them to Mr. E. W. 

 Binney, who pronounced them to be Liassic. Mr. Binney after- 

 wards visited the district and recorded the result in a paper read 

 before this Society^. I have since discovered but one section not 

 described therein, in a brook between Great Orton and Plat. It is 

 composed of dark shale with limestone bands. Ammonites John- 

 stoni was found there, as also in Thornby Brook and at Quarry Gill, 

 near Aikton. By Mr. E. B. Brockbank's assistance I was enabled 

 to obtain evidence of the thickness attained by the Lias between 

 Great Orton and Plat, a spot nearly at its centre. A document, from 

 which I have already quoted, which has been preserved by the Stordy 

 family of Great Orton, gives the following details, according to a 

 copy of it kindly made for me by Mrs. Hannah Pearson, of Station 

 Hill, "Wigton. In the year 1781 a boring was made by JohnBrisco, 

 of Crofton, in John Stordy 's Gill close. A blue stone was found 

 18 feet from the surface, and " different stone, mostly bluish," till 

 they arrived at a depth of 228 feet. Then they pierced the "red 

 stone or clay, sometimes mixed with veins of white " (which I sup- 

 pose to be the Gypseous Shales), till they came to a depth of 

 360 feet. 



The Lias area forms a plateau, with a slightly greater general 

 elevation than is attained immediately outside it. This plateau-like 

 character is better marked in the country between Aikton and Great 

 Orton than eastward of the latter place. No person standing about 

 "Wiggonby, near the southern border of the Lias, can fail to notice the 

 difference between the flat-topped plateau northward and the rolling 

 drift-ridges to the south. But though this change of feature makes 

 it possible to map the Lias boundaries with some approach to a 



. * Andrew Miller, Nealhouse. 

 t Of Moor Park, Crosby, near Maryport. 

 | Quart. Journ. Geol. Soc. vol. xv. p. 549. 



