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



stone Post is another stratum of Sandstone, 18 fathoms in thickness, 

 which crops out into the diluvium between the Howdon and Percy 

 Pit, and is no more seen on this line of section, except on the dip side 

 of the Main Dyke, where it is assumed to have been thrown in again 

 to fill up the chasm occasioned by the depression of the strata on the 

 north side of the Dyke. It is also assumed, that another stratum of 

 Sand Stone of 9 fathoms in thickness overlies this Post, with 11 fathoms 

 of Metal Stone intervening. This is assumed in consequence of those 

 two strata of Sand Stone having been found in sinking the B Pit, at 

 Hebburn, as shewn in Section No. 4. 



The Grindstone Post also crops out into the diluvium between the 

 Howdon and Percy Pits, and does not again appear on this line of sec- 

 tion, until it is thrown down by the Main Dyke; on the north side of 

 which, at the village of Backworth, it forms the pavement of the street, 

 and is also quarried for building. Beyond this point, the Grindstone 

 Post does not exist on this line of section, as it crops out immediately 

 on the north side of Backworth village. 



The Seventy Fathom Post may be considered as comprising all the 

 strata of Sand Stone which intervene between the Grindstone Post and 

 the Main Post. At the lowest point where the section commences, it 

 is in three divisions, separated by two strata of Metal Stone. This post 

 is thrown out by the 40 fathom upcast Dyke to the north, afterwards 

 described, in Collingwood Main Colliery, and does not re-appear on the 

 line of section until we arrive on the north side of the Main Dyke, in 

 Backworth, Earsdon, and Holywell collieries. It crops out before it 

 reaches Holywell Bum, where it is thrown in again by the Briar Dean 

 Burn or 35 fathom Dyke, from whence it probably ranges as far as the 

 river Blyth. It will be observed, that this post is split into five divi- 

 sions immediately on the north side of the Main Dyke. But two of 

 the divisions become united again before they reach Holywell Pit. 



The Main Post. — This Post is thrown out by the 40 fathom upcast 

 Dyke already mentioned, in Collingwood Main Colliery, for the space 

 of 150 yards, where it is thrown in again by an 1 1 fathom downcast 

 Dyke. It then runs immediately below the soil to Billaw Mill where the 



