Geology. — On the Order of Succession of Rocks. 343 



prismatic forms extensive areas ; at other times existing in amor- 

 phous masses which put out numerous branches into the adjacent 

 rocks, ejected from those masses, as it were, with intense heat 

 and velocity. There is a singular mineral vein of this kind in 

 England, which we have personally traced more than fifty miles, 

 passing easterly from the county of Durham, to the sea in 

 Yorkshire, between Whitby and Scarborough. This Dyke, as it 

 is there called, cuts, in its upward course, through the carbonifer- 

 ous limestone. No. 9, the coal beds, and many other superin- 

 cumbent beds into the oolitic series. It appears to be broader the 

 nearer it approaches to the primary rocks. Mr. Bakewell ob- 

 served it 30 (eet broad at Sillow Cross, and twice that width 

 further west. When we reflect that all modern lavas are poured 

 out from volcanos, which are but the vents of a fierce igneous 

 action striving in profound depths, and that lavas in various parts 

 of the world have been observed to have flowed out to the sur- 

 face, through the granite, the lowest of all rocks ; we can but 

 concur in the now universally received opinion, that these trap 

 or intrusive rocks have an igneous origin, and that they all, at 

 various periods, have been projected from those cavities which 

 are inferior to all the known rocks, and which are unsearchable 

 to man. These ancient eruptions having, like the modern ones, 

 taken place at separate periods, we of course find the evidences 

 of them irregularly distributed through the geological series. It 

 is for this reason we have excluded them from a system of beds 

 remarkable for its regularity in all parts of the world, where its 

 members have been recognized ; a systematic regularity, the im- 

 portance of which no one can be insensible to, who is not dis- 

 posed to attribute invariable succession to mere chance. The 

 geological phenomena consequent upon the origin and action of 

 these intrusive rocks, forming one of the most conspicuous 

 branches of geology, we shall hereafter have frequent occasion 

 to return to them. 



We now feel bound to offer some explanation to our readers, 

 of the nomenclature contained in the tabular view. When we 

 come, in another number, to treat successively of the different 

 beds, we shall offer explanations of the names by which we 

 have at present designated them, being those by which they 

 are known in the various geological treatises in the English 

 tongue. That this nomenclature may be hereafter greatly modi- 



