NORTH AMERICA (GEOLOGY. 1 



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remarkable sandy desert, whose width is between 500 

 and 600 miles.* An equal degree of simplicity cha- 

 racterizes the structure of that portion of the North 

 American continent, which still remains to be men- 

 tioned. The south-eastern boundary of the secondary 

 basin just described, following the irregular base of 

 the AJleghanies, from the Alabama river to fort Ann, 

 near lake Champlain, is the north-western limit of an 

 extensive tract of transition, which runs still farther 

 northward, pursuing the eastern shore of lake Cham- 

 plain, in a narrow belt, to Canada. It varies in width 

 from twenty to upwards of 100 miles, and its strati- 

 fication follows a north and south, or a north-east and 

 south-west direction, with an inclination from the 

 horizon of less than 45. The mountains of this 

 tract consist of long, parallel ridges, whose outline is 

 almost one unbroken line, and whose sides decline in 

 gentle slopes. In Pennsylvania, it embraces an ex- 

 tensive and invaluable deposit of anthracite coal, and 

 one also in the state of Rhode island, which, though 

 considerably removed from the present district, never- 

 theless, belongs to the same class of rocks. Iron and 

 lead are likewise among the contents of this forma- 

 tion. To the transition upon its eastern side-succeeds 

 the great primitive country of the United States. 

 Towards its southern extremity, in the Carolinas and 

 Georgia, its width is above 150 miles ; but as it ad- 

 vances northward through the Middle States, where 

 the transition is widest, its breadth decreases : when 

 it reaches the Highlands of New Tork, it begins to 

 widen, and spreads over nearly the whole of New 

 England, continuing into Canada and New Bruns- 

 wick, probably to the mouth of the St Lawrence. To 

 this primitive mass, also, belongs all the mountainous 

 country between lake Champlain, the river St Law- 

 rence, and lake Ontario, which is separated from the 

 foregoing district by the narrow belt of transition 

 occupying the eastern side of lake Champlain. The 

 strata of this formation run from a north and south to 

 a north-east and south-west direction, with a dip to 

 the southward of more than 45. Its greatest eleva- 

 tions are found in the White mountain range, where 

 a few peaks attain a height of more than 6000 feet. 

 The surface presented through the primitive country 

 is that of circular and smoothly swelling masses, 

 with rounded tops. It abounds, throughout its whole 

 extent, and especially in New England, where it has 

 been more carefully explored, with all those simple 

 minerals, existing in similar formations in other coun- 

 tries. Its metallic deposits, which are mostly in the 

 form of beds, are numerous and valuable; among which 

 may be mentioned magnetic and hasmatetic iron ores, 

 native gold, and copper pyrites. The eastern boun- 

 dary of the primitive is a line commencing near 

 Alabama river, and running northward through 

 Augusta, upon the Savanna river, west of Camden, 

 South Carolina, and near Aversboro, North Carolina, 

 by Richmond, Philadelphia, and Trenton, and north 

 of New York, pursuing the shores of the Atlantic. 

 Within the primitive country thus defined, however, 

 there exists, besides the transition tract of Rhode 

 Island, a narrow strip of secondary, commencing at 

 Northfield (Mass.) upon the Connecticut, and run- 

 ning through to the sea at New Haven, where it ends 

 to recommence again upon the south side of the 

 Hudson from whence it pursues a south-westerly 

 course to the Rappahannock. It consists of the old 

 red sand-stone, upon which repose, at several places, 

 what are now regarded as the older volcanic rocks, 

 amygdaloid and green-stone trap. The same forma- 

 tion also occurs farther north, in Nova Scotia. To 

 complete our present sketch of the United States, 

 we have only to notice what has, till lately, been 



* Long's Expedition to the Rocky Mountains. , 



denominated the tertiary formation of North America. 

 It commences to the north in a clustre of islands 

 situated south of cape Cod, and proceeding south, 

 embraces Long Island, and, recommencing upon the 

 continent in the northern part of New Jersey, 

 covers the vast extent of country between the coast 

 and the Alleghanies, and is finally terminated in the 

 Mexican sea. North of the Roanoke, the tide 

 penetrates completely across it to the primitive ; 

 but, farther south, it becomes more elevated. It 

 consists of beds of sand, clay, and marl, which con- 

 tain lignite, the remains of marine animals, and vast 

 quantities of shells. The distinction of this exten- 

 sive district into two formations the upper secon- 

 dary, or a formation contemporaneous with the 

 super-medial order of Phillips and Conybeare, and 

 the tertiary was first established by professor Vanu- 

 xem and doctor Morton. The former of these con 

 sists of marl, highly argillaceous, and containing 

 greenish particles, analogous to those which are 

 found in the green sand, or chalk, of Europe. Its 

 prevalent colour is a dark green, sometimes rendered 

 brown by per-oxide of iron. It abounds in the fol- 

 lowing genera of shells, viz. terebratula, gryphoea, 

 exogyra, ammonites, baculites, and belemnites. It 

 occupies a great part of the triangular peninsula of 

 New Jersey, formed by the Atlantic, and the Dela- 

 ware, and Raritan rivers, and extends across the 

 state of Delaware from near Delaware city to the 

 Chesapeake ; appears again near Annapolis, in 

 Maryland ; at Lynch's creek, in South Carolina ; at 

 Cockspur island, in Georgia; and several places in 

 Alabama and Florida. It has also been noticed in 

 numerous other localities, when the tertiary and 

 alluvial coverings have been removed by natural or 

 artificial causes ; and there are good grounds for the 

 opinion, that beds of ferruginous sand extend nearly 

 the whole length of the Atlantic frontier of the 

 United States, south of Long island, though, for the 

 most part, concealed by the different members of the 

 tertiary class. The tertiary embraces the islands of 

 Nantucket, Martha's Vineyard, Long Island in part, 

 Manhattan island, together with a fractional part of 

 the adjacent coast of New York and New England. 

 It likewise forms the Neversink hills, in New Jersey, 

 the southern part of the peninsula of Maryland, from 

 whence it pursues a southern direction, forming an 

 almost continuous superficial mass over the country 

 between the Alleghanies and the coast, to the Mexican 

 sea. It is composed of lime stones, with mixtures of 

 clay or sand, or both, in variable proportions'; of 

 clay alone ; of clay with sand, forming loam ; of 

 beds of gravel, or of buhr-stone. It is marked by 

 littoral shells, analogous to those of the tertiary 

 deposits of the Paris and English basins. The fossils 

 of the tertiary are generally found within fifteen or 

 twenty miles of the primitive, the intermediate space 

 being filled with clays of various kinds. The highest 

 point to which this formation rises, is about 250 feet. 

 It is near the line of junction with the primitive on 

 Savannah river. Over the surface of these forma- 

 tions is everywhere distributed alluvial gravel, con- 

 taining large masses of granite and other primitive 

 rocks ; and in many places upon the coast it is 

 covered with accumulations of alluvial sands.* 



Concerning the geology of the southern part of 

 North America, we are still exceedingly deficient in 

 information, the attention of travellers and mineralo- 

 gists having been so much absorbed with the richness 

 and variety of the metallic deposits of Mexico, as 

 almost wholly to have overlooked its geological 

 features. We cannot, perhaps, better perform this 



* Geology of the United States, by William Maclure (Phil., 

 1817), Jouru. Acad. Nat. Sci. (Phil, voi. vi.}, and American 

 Journal (vol. vii. and xiii). 



