lO BAKERS NORTH YORKSHIRE. 



' sugar limestone.' A few miles further north the rich mining 

 tract of Alston Moor furnishes the following section of the beds 

 of this series : — 



feet. 



Tyne bottom limestone 24 



Alternations of shales and sandstone 74 



(Here the Basalt occurs) 



Jew lime 24 



Alternations 26 



Little Lime 18 



Alternations 90 



Smiddy Lime 31 



Sandstone 12 



Limestone 25 



Alternations 21 



Robinson's lime 21 



Alternations 12 



Great limestone of Melmerby Scar 132 



Alternations and coal 24 



Limestone 12 



Alternations 165 



Limestone 7 



Alternations and coal 221 



Limestones 18 



Alternations 234 



Total thickness of the series, 1,191 feet. 

 312 feet calcareous, 879 feet non-calcareous. 

 The Teesdale Basalt or Whin Sill. — A huge mass of rock 

 which has owed its origin to igneous agency, and which is 

 known locally by the name of the Whin Sill*, extends from the 

 neighbourhood of Brough in Westmorland into the district 

 round the head waters of the Tees, Wear, and Tyne, and from 

 thence, with some interruptions, is continued as far north as the 

 Northumbrian coast, near Alnwick. It attains its greatest 

 development at the Caldron Snout, where it is from 200 to 300 

 feet in thickness, being in Tynedale about 120 feet thick, and 

 at the head of Hilton Beck, which is only six miles westward 

 from the Caldron Snout, becoming diminished to 24 feet. 

 Generally the deposit is remarkably layer-like in character, con- 

 formed to the plane of the stratification of the neighbouring 



* Whinstone is the local name for basaltic rock, the Scottish quhyn- 

 stane. Sill is the Saxon syll, syle, the French seuil, the flat piece of tim- 

 ber or stone at the foot of a door or the bottom of a window. 



