Lesley.] 466 [December. 



sey, Pennsylvania, Maryland, Virginia, and East Tennessee to Ala- 

 bama, '*a narrow continuous" belt; for, with one exception, here- 

 after to be described, itis really such. And it would be quite as diffi- 

 cult to point out another deposit strictly " analogous to the Brandon 

 lignite," along all these many hundred miles, excepting the one just 

 discovered in Southern Pennsylvania. There may be others not yet 

 made known. But a great number, literally thousands of shafts, and 

 open quarries, have been made in this ore belt in these different States, 

 during the last hundred years, from some of which hundreds of 

 thousands of tons of stuff have been excavated ; and yet even the 

 presence of a fossil leaf, or any other slight trace of tertiary vegeta- 

 tion, is almost or quite unknown. Quantities of dark and even black 

 clay have been obtained ; but in all instances, so far as I am aware, 

 the coloring matter has been manganese rather than carbon. The 

 futui'e may reveal much which we do not expect; but enough has 

 been done to prove the rarity of lignite in the ore belt. 



We must therefore carefully separate these sporadic occurrences of 

 lignite from the general occurrence of iron ore, in our discussion. 



I think it can be shown, also, that we must keep quite as separate 

 the lignite and the clays. And I think it can also be shown that 

 the clays are to be connected closely with the ores, instead of with 

 the lignite, if we are to reach clear views of the whole phenomenon. 



These are the principal features of the great ore belt of the At- 

 lantic States : 



1. It occupies a narrow strip of surface, along the Great (Lower 

 Silurian) Valley, which begins in Canada, and ends in Alabama. 



2. It hugs the southeastern margin of the Great Valley, and lies 

 at and against the foot of the Mountain Barrier, which, as is well 

 known, shuts the Great Valley in from the Atlantic seaboard ; a bar- 

 rier, known by various names, such as the Green Mountains, the 

 Highlands, the South Mountains, the Blue Ridge, and the Smoky 

 Mountains ; but which is in reality and geologically considered, one 

 continuous range or ridge of rock. 



3. It lies, therefore, over the lower contact of the Lower Silurian 

 limestones with and upon the rocks of the Great Barrier range ; and 

 is, therefore, in some loay or other, genetically involved in that con- 

 tact. It therefore belongs geologically to the Lower Silurian lime- 

 stone formation, and especially to the lowesf member of that for- 

 mation ; and cannot in any sense, as an ore belt, be of tertiary age, 

 without a plain violation of the canons of structural geology. 



4. It consists everywhere of two parts, more or less easily dis- 



