On the Classification of the Fossiliferous Slates of North Wales, Cumberland, Westmoreland and Lancashire (being a Supplement to a paper read to the Society, March 12, 1845)
Before I proceed to the examination of details (and I wish to avoid details as far as possible), I may state in a few words what are the leading objects of the following paper. 1. I wish to describe some new facts (observed during the past summer) that appear to connect together, and give a consistency to, various sections through the older Palæozoic rocks, which have been exhibited and explained during the meetings of former years, and several of which have been published in the Proceedings and the Journal of the Society. Under the term Cambrian System I at present include (in accordance with the original use of the words) all the rocks in the uncoloured portions of Sir R. I. Murchison's Silurian Map; indeed all the older slate rocks of North and South Wales beyond the limits of the Silurian system, as well as all the older slate groups of the Cumbrian mountains. 2. I shal endeavour to give an approximate view of the successive older groups in South Wales, so as to put these groups in approximate coordination with those of North Wales. 3. I wish to explain the evidence on which we may approximate to the thickness and natural grouping of the successive Cambrian deposits, so as to put them in their true relation to the lower groups of the Silurian system, as published by its author. 4. From a review of the leading facts, physical and zoological, and a comparison of them with the development of