271 



County of Londonderry. 



No. 



39 

 40 

 41 

 42 

 43 

 44 

 45 

 46 

 47 



48 

 49 

 50 

 51 

 52 



Name of Locality. 



Slieve Gallion, 5 miles S.E. 



of Draperstown, . 

 Craig nashoke, 5 miles N.W. \ 



of Draperstown, . . . J 

 Eden, 6 miles S.E. of Dun- 



given, . . . .. 

 Benbradagh, 3 miles N.E. ) 



of Dungiven, . / 



Kilhoyle, 6 miles N. E. of) 



Dungiven, / 



Donald's Hill, 6 miles S.E. j 



of Newtownlimavady, . . j 

 Keady, 11 miles N. E. of) 



Newtownlimavady, . . j 

 Benyevenagh, 5 miles N. E. \ 



of Newtownlimavady, . j 

 Umbra, 10 miles N. E. of 



Newtownlimavady, on north 



shore, 



In the plateau of low land be- 

 tween Lough Neagh and the 

 base of Slieve Gallion the 

 Chalk is quarried in several 

 places ; the heights at which it 

 stands in some of them are : — 



Carmean, 3 miles N. of Mo 



neymore, . 

 Gortagilly, 1J miles 



Money more, . 

 Tamlaght, 3 miles S.E. of 



Moneymore, .... 

 Ballywholan, 1^- miles N. of ) 



Stewartstown, . j 



Mullantain, 1 mile S. E. of) 



Stewartstown, . j 



N. of J 



Height of top 

 of Chalk. 



Thickness of 

 Chalk. 





Feet. 

 1622 



1394 



Feet. 

 22 | 



3 { 



Slieve Gallion, 

 top of trap, 



Craignashouk 

 Mountain, 



1000 



3 



Eden Mountain, 



1120 



12 



Benbradagh, 



900 





Ballyness Moun- 

 tain, 



900 



20 



Donald's Hill, 



550 



33 



KeadyMountain, 



? 



? 1 



Benyevenagh 

 Mountain, 



Sea 



50 





260 



? 





300 



? 





175 



30 





185 



? 





300 



? 





of next 

 itain. 



tn . 



si 



|i 



<u 





K 



H 



Feet. 



Feet. 



| 1622 



100 



I 1996 



379 



1286 



286 



1531 



411 



\ 1227 



327 



1315 



418 



1110 



551 



| 1260 



? 



? 



? 



The thickness of the basalt in the preceding table was determined in 

 this way : — Where the chalk lies level, take the height of the chalk 

 from the height of the summit of the mountain, the remainder is the 

 thickness of the basalt. "Where the chalk dips inwards under the 

 mountain at a low angle, the angle of the dip, and the distance of the 

 nearest limestone quarry to the summit, were taken, and from those 

 two items a third item was made out, that is the amount perpendicu- 



