Mr. Bubble's Synopsis of the Newcastle Coal Field. 229 



DYKES ON THE LINE OF SECTION, No. 1, 



BEGINNING AT THE DEEPEST POINT AT JARROW SLAKE. 



The High Main Seam rises for a short distance at an angle of 10°, 

 when it is thrown up to the north by a Dyke 12 feet, and at a short dis- 

 tance further it is thrown up again by another Dyke 6 fathoms. Then just 

 on the south bank of the river Tyne it is thrown down 15 fathoms. The 

 seam then goes on, without interruption, at a moderate rate of rise to 

 about 500 yards north of the Percy Pit, when a sudden degree of ascent 

 takes place, and throws the seam into a sort of ledge for 140 yards. It 

 then stretches away again, at about its ordinary rate of rise, till it is 

 thrown out at the surface by a 40-fathom Slip-dyke, 200 yards to the 

 north of the Chirton Pit. 



I shall here pause to notice this 40-fathom Dyke. It has been traced 

 from Willington Colliery through Percy Main and Collingwood Main 

 Colliery — through North Shields and the Black Middens into the sea, 

 below Tynemouth Barracks. It is ascertained to be an up-cast of 40 

 fathoms to the north in Collingwood Main, but it diminishes in size as 

 it passes through Percy Main and Willington Collieries, towards its 

 junction with the Main Dyke, a little to the north west of the village of 

 Long Benton, behind which it passes. After being thrown out to the 

 surface by this Dyke, the seam is wanting along the line of section for 

 about 150 yards, when it is brought in again by a down-cast Slip-dyke 

 of 11 fathoms. It then proceeds, with very little variation as to level, 

 to the Main Dyke, which throws it down apparently about 140 fathoms. 

 From the north side of the Main Dyke the seam rises rapidly for about 

 half a mile, becoming gradually more level, till at length it becomes 

 nearly flat, and in some places dipping to the north, as is proved by the 

 workings in Holywell and Backworth Collieries. Its next depression is 

 near the village of Holywell, where it is supposed to be thrown down 

 about 35 fathoms by the Briar Dean-Burn Dyke. 



SECTION, No. 2, PLATE XXI. 

 This section commences at Redheugh, on the south bank of the 



