divided into five principal regions. These we will treat of in a geo- 

 graphical rather than geological order ; first defining the limits of 

 each respectively, with as much precision as in the imperfect state 

 of knowledge on the suhject can be attained, and then in general 

 terms describing the geological features by which they are, to a cer- 

 tain extent, severally distinguished. 



(1.) — The first of these, which may be called the tertiary marl re- 

 gion, embraces nearly all that portion of the state included between 

 its eastern boundary, the Chesapeake bay and the Atlantic, and a 

 hypothetical line intersecting the principal rivers at their lowest falls. 

 Various beds of clay and sand, nearly horizontal in position, abound- 

 ing in fossil shells, and the remains of large marine animals, form 

 the characteristic strata of this division of the state, while occasional 

 bands of iron ore, and beds of green sand, and a small portion of 

 gypsum, occurring in connexion with one of the fossiliferous de- 

 posites of the region, are among its other materials of value. 



(2.) — The second division is comprised between the hypothetical 

 line above mentioned and the western flank of the Blue Ridge — in- 

 cluding under this title the range very improperly denominated the 

 Alleghany mountain in Franklin and Patrick counties. According 

 to the delineation of Mr. M'Ulure, by whom the first attempt was 

 made at marking out the great geological divisions of North America, 

 the rocks of the Blue Ridge and a narrow adjacent belt of territory 

 should be regarded as belonging to the primary system of geologists 

 — while a large portion of the area between this and the belt of un- 

 equivocally primary character which ranges along the lower falls of 

 our rivers on the east, is to be looked upon as the ecpiivalent of the 

 old red sandstone rocks of Europe. Others who have attempted to 

 sketch the outlines of our principal geological formations, have "with 

 even less approach to accuracy, confounded all these strata under 

 the sweeping denomination of primary — and have thus given to the 

 diversified and extensive region whose limits are above described, 

 the distinctive appellation of the primary region of Virginia. Such 

 a view appears to have been adopted by the authors of the map of 

 our state, the brief geological sketch appended to which describes 

 the Blue Ridge as the western boundary of the primary. A more 

 recent writer also, professing to derive his views from an actual 

 examination of the structure of this mountain, has contributed to 

 confirm the prevailing error by proposing as an appropriate name for 

 the Blue Ridge— the title of the Atlantic primary chain. It is deeply 



