278 Mr. Fareifs Statement of Geological Facts 



Gobbins in Magee Isle, p. 62 : and Wood Coal or com- 

 pressed bituniinated Wood, usually in thin seams between 

 the basalt beds, at Mount-Druid near Ballintoy, p. p7, at 

 Killymorris near the cenrre of the County, at Ltuimeaeh, 

 also near the E shore of Lougli Neach (between Ballin- 

 derry and Crumlin), and near PortiDore, p. 89, at which 

 last place two beds of 23 feet thick, a third 9 feet, and a 

 fourth still lower was penetrated i8 inches by the borting 

 rods, at SO yards deep, before the operation was discon- 

 tinued, p 90: and at Beuirore-head, in a considerable stra- 

 tum between, two rows of basaltic pillars! p. 90. Note. 



The shrinking and opening of fissures and caverns in the 

 Limestone, beneath these Basalts (m common with all thick 

 calcareous strata which I ever saw,, which the water-swal- 

 lows at Red Hall and near KiKvalter (p. 71) serve to illu- 

 strate, may well accoimt for ihe sinking of the Basaltic 

 surface into Funvel-skaped holioivs*, at Broom-mount in 

 Soldier's 'J'own and elsewhere, mentioned App. p. 112; 

 but where it was by no means necessary, to resort to the 

 improbable suppositions of " the softening and carrying 

 away of some understratum, probably Limestone, by the 

 action of subterraneous running waters," to account for 

 these local, and in some districts very common depres- 

 sions of the surface: and which seem to have nothing 

 in common with the decomposing cores and semi- 

 spherically-shaped cavities t left on the surface of Basalt, 



* Among the numerous facts collected, and further attainable, towards 

 my proposed Mineral Hiiloiy of Derbyshire (should an adequate interest 

 and encouragement arise and offer, to render it prudent on my part ever 

 to resume it), which coild not find a place in the published Report to the 

 Board of Agriculture, the several conical depressions in the 3rd Toadstone 

 (or Basalt) near Water-Swallows in Fairfield, owing to the shrinking of the 

 thick 4th Limestone beneath, remain to be mentioned, as instances similar to 

 those in Antrim. A depression or elliptical Sankun; or Basin of small extent 

 and depth, on the Ut Grit Rock SW of Overton Hall, lately presented itself 

 to my notice, in sur\ eying and levelling in the Fields in that part, for Sir 

 Joseph Bank's large Mineral Maps and Sections wh ch I have in hand, and 

 probably indicates a cavern or large shake hole in the 1st Lime Rock be- 

 neath, into which this thick grit-stone Rock has become locally depressed. 

 Hell-Kettles S of Darlington in Durham are, doubtless, two sunk places of 

 the upper clayey stratum, into the shrunk magnesian Lime Rock beneath. 

 Nor is it uncommon, owing to the unequal contraction of the lower cal- 

 careous beds (where there is no superincumbent stratum) to find depressions 

 in calcareous soils, as may be seen on a grand scale about Stanstead NE of 

 Brighton, in the up()er Chalk; in Norfolk near to Mr. Colhourn's former 

 residence: on a smaller scale on the Chalk Hills SW of Wendover, Bucks.: 

 and even in Gypseous tracks, according to the 1st Edit, of Jameson's " Geog- 

 nosy,'' p. 34 and 17'2. 



■f The several Rock Basins, and some of the Stone Chairs on the 1st Grit 

 Rock, where exposed in blocks, in Deibyshire, seem ov^ing wholly or in 

 great part, to decomposed or loosened Lums or Nests of Mica plates, such 

 as are noticed in my Report, vol. i. p. 4CG. 



in 



