460 NOTES. 



strata are attended with many peculiar circumstances, very different from their 

 associates, 3, 5, 7, 9. These peculiarities are : 



1. Toadstone is similar to Iceland Lava both in its appearance and chemical 

 qualities. 2. It is extremely variable in thickness. 3. It is not universal. 4. It 

 has no fissures corresponding to those in limestone. 5. It frequently fills up the 

 fissures in the stratum underneath it, as at H, and the bottom of the shaft s, which 

 enters a fissure of toadstone that in a liquid state has flowed into the limestone 

 stratum, numbered 9. Throughout the limestone strata of Derbyshire the fissures 

 we have marked correspond ; and in these fissures, and between their lamina, the 

 minerals are found. The mines in the fissures are called rdke-wor ks ; the mines in 

 the laminae are called pipe-works. Thus in the stratum No. 3, we find Yatestoop 

 mine ; the Portaway and Placket mines are in No. 5. ; in No. 7. we have Mosey- 

 meer, and in No. 9 Gorseydale mines ; Hangworm mine is on Bonsai Moor. The 

 stratum No. 5 bassets and forms the surface of the earth at Foolow and Bonsai 

 Moor. No. 8 bassets and becomes the base of the land called Grange Mill. No. 

 3 again bassets and becomes the districts Trogues Pasture to the right, and 

 Wensley to the left of the great shaft sunk at o and trending below ground to the 

 fissure G in No. 5. Here we have a beautiful illustration of the genius of geological 

 engineering. A spring occurs at I in the fissure G, No. 3, too powerful to be 

 overcome, or too expensive to be kept under ; accordingly a shaft is sunk at o 

 higher up the acclivity. The miners pioneer to a, descend to the fissure G by 

 driving a gallery or gate, as they term this tunnel, and this is a common practice, 

 and never fails in producing dry work in the stratum No. 5, for the close texture 

 of the toadstone will not allow the water in the seam between 3 and 4 to percolate 

 its impervious mass, although the pool may accumulate from 10 to 15 fathoms in 

 No. 3. If the water in 3 rise not to the horizontal level L L, it can never incom- 

 mode the shaft o a. The grand geological fact elicited here is, as regards capillary 

 attraction, that toadstone turns water, is free from fissures, nay, sometimes fills 

 up fissures, as at s and H, which the miners call troughing. In the Slack and 

 Salterivay mines on Bonsai Moor, some forty years ago, these cros.-ralte fissures 

 were noticed by Mr. Whitehurst. Their occurrence in other mines need not 

 astonish geological engineers. 



In other districts in Britain, we find that the coal formations sometimes repeat, 

 in precisely the same order, arid in nearly the same thickness, the following earths 

 and minerals : sandstone, bituminous shale, slate clay, clay iron, stone, coal ; or 

 the coal is covered with slate, trap, or limestone, or rests upon these rocks. The 

 strata generally follows every irregularity of the fundamental rock on which they 

 rest j but in some instances their directions appear independent, both of the surface 

 of the rock, and of the cavity or hollow in which they are contained, and in general 

 take a waved outline, seldom rising greatly above the level of the sea. 



We have now, however, merely represented the general arrangement of the 

 strata ; not all the particular circumstances accompanying them, with respect to 

 their several fractures, dislocations, &c. ; but it will enable us to reason upon the 

 chemical effects of water upon limestone and gypsum rocks, where we meet with 

 caverns, caves, and extensive fissures, that reach sometimes to the surface, some- 

 times dip to a greater or less distance, and afford channels for great springs and 

 subterranean rivers. These caves in the gypsum and chalk formations vary in 

 magnitude from a few yards to many fathoms in extent, forming upon the surface 

 of the ground, when their superincumbent roofs give way, those funnel-shaped 



