268 



the lower, and thus was produced a more level bed for the chalk than 

 there had been for the new red sandstone. The chalk, indeed, in. ge- 

 neral does affect a horizontal position, both in the main body, and in 

 localities where detached patches of it exist. 



The greatest thickness we know of the chalk of Antrim is at "White- 

 park, near Ballintoy, where it is visible about 210 feet thick over sea 

 level ; but to show its thickness at many localities I have made the fol- 

 lowing tabular form. In it I shall follow the rock through its undula- 

 tions, as seen along near the coast, and compare it in its course with 

 the level of the sea. In this table the heights of the upper surface of 

 the chalk, above the Ordnance sea level, are recorded at stations, which are 

 marked upon the ]U!ap of Antrim, PL XXII., at every four or five miles 

 asunder, as a quarry or a natural opening presented itself. I consider 

 this form, and the numbers prefixed in each case, useful for reference. 

 The first column shows the number of the station; the second is its 

 name ; the third is the height of the chalk at the upper surface over 

 sea level ; the fourth is its thickness at each station so far as it can be 

 either measured or estimated with facility : the fifth column is the 

 height of the nearest hill or mountain, where the thickness of the over- 

 lying trap may be found at any station; the sixth is the height of 

 mountain above sea level; the seventh is the thickness of the trap 

 in that mountain. At many of the stations the thickness of the chalk 

 could not be made out with accuracy, on account of the base of the 

 rock being covered up with a talus, or its not being quarried to the 

 bottom : — 



Table, showing the Heights of the tipper Surface of the Chalk above Sea 

 Level, at certain Localities, together with its Thichiess, where attain- 

 able ; also the Heights of the adjacent Mountains, and the Thichiess 

 of the Basalt. 



County of Antrim. 



So. 



Locality of Station. 



%4 



d, zn 

 c u 



11 



= 3 



Cm 

 O 



to 



Name of adjacent 

 Mountain . 



bt g 

 '5 « 



Thickness of 

 Basalt. 







Feet. 



Feet. 





Feet. 



Feet 



1 



Clare, | mile S. E. of Moira, 



150 



62 



No hill near, 



none. 



none. 



2 



Balmer's glen, 2 miles N. E. "1 



230 





Spence's fort, 



266 



72 



3 



Aughnahough, 3 miles X. W. ) 



; 660 





White Mountain, 



820 



.270 



4 



Collin Well quarrv, 4 miles ) 

 S. W. of Belfast, ... J 



J 650 





Collin, 



1081 



785 



5 



White Rock quarry, 2 miles ) 



680 



130 



Black Mountain, N., 



1272 



813 



6 



Ballygomartin. 2 miles N.W. ) 

 by W. of Belfast, . . . j 



720 





Divis Mountain, 



1567 



• 



1538 



