266 Mr. Weaver on the 
latter rock being principally observable at the surface. Both here 
and on the north side of the peninsula, the magnesian limestone is 
traversed by small veins of brownspar, and it contains cavities filled 
or lined with calcareous spar and brownspar. 
§ 165. Limestone is visible at low water, in three places on 
the shore beneath Booterstown, on the south side of Dublin bay* 
in strata dipping 15° to 20° toward the north-east. It is bluish 
grey, foliated granular, with frequent small veins of brownspar* 
At Williamstown on the coast, farther east, granite rock appears ; 
and about two perches north of it is a low insulated rock of lime- 
stone, of the same description as that under Booterstown. 
§ 166. In the line of the Dodder, between Classon’s bridge 
and Miltown bridge, magnesian limestone, traversed by veins of 
brownspar and associated with common grey limestone, may be 
observed dipping at an angle of 5° toward the north ; while at a 
short distance to the south, the subjacent granite becomes visible* 
But, in the whole tract between the Dodder on the south and the 
Liffey on the north, as well as to the north of this river, in which 
so many quarries are opened both for calp and for limestone, the 
general direction of the beds is east and west, with a dip to the 
south at an angle seldom, exceeding 15° to 20 ? * The same dis- 
position is manifested, more to the west, in the line of the Grand 
Canal, extending toward Newcastle \ yet, near Hazlehatch, as- 
already remarked, (§ 135*) the limestone where it adjoins the sub- 
jacent rock, which is here principally greywacke slate, dips to the* 
north, or according to the natural declivity. I have before observed,. 
(§ 155.) that this conformity of position to the declining surface 
of the contiguous rock, is general throughout the field, whether the 
limestone rest upon granite, on clay slate, or on sandstone, which 
