Geological Relations of the East of Ireland. 12*7 
direction passes through the counties of Monaghan and Armagh to 
the north-eastern extremity of Down. This tract is composed 
principally of the clayslate and greywacke formation, connected 
with the granite and syenitic granite of the mountains of Morne, 
and sustaining a few isolated patches of floetz limestone in its in- 
terior ; as well as supporting, on its western and southern sides, 
the more extended sheet of that rock, by which it is in a great 
measure flanked in those quarters. 
§ 10. We may obtain some idea of the general elevation of the 
great Limestone Plain, by considering the ascertained levels of the 
Grand Canal, of the Royal Canal, and the various levels taken by 
the several engineers who were employed in surveying the bogs of 
Ireland ;* and for some additional data upon this subject, I have to 
express my acknowledgments to the Directors General of Inland 
Navigation in Ireland, and more especially to Mr. Killaly, their 
engineer, ■f* The results are to be found in the following Table, in 
which all numbers refer to the level of high water mark in Dublin 
bay. 
* See the Reports to Parliament by the Commissioners, and their Engineers, respecting 
the Bogs of Ireland. 
+ See the Reports to Parliament by the Directors General of Inland Navigation in 
Ireland, and their Engineers. 
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