CONTENTS. 
PART II. 
CHAPTER XIX. 
DESCRIPTIVE GEOLOGY. 
PHYSICAL GEOGRAPHY OF NORTH AMERICA. 
Extent of North America. — Mountains. — Rocky Mountains. — 
Atlantic Series. — The Blue Ridge. — The Appalachian. — The 
Alleghany. — The Eastern System. — Atlantic Plain. — Central 
Basin. — Influence of Geological Structure on Society.— Influ- 
ence of Geological Formations on Scenery . . Page 206 
CHAPTER XX. 
GEOLOGY OF THE UNITED STATES, 
PRIMARY ROCKS OP THE UNITED STATES. 
Primitive Rocks.— Prof. Hitchcock's Arrangement. — Stratified 
and Unstratified.— Distribution of Primary Rocks.— In New- 
England. — In the Middle States. — Syenitic Porphyry. — Pri- 
mary Stratified Rocks. — Gneiss. — Mica Slate. — Talcose 
Slate. — Granular Limestone. — Minerals in Granitoid Rocks 
218 
CHAPTER XXI. 
GEOLOGY OF THE UNITED STATES. 
TRANSITION ROCKS. 
Definition. — Clay Slate. — Its Distribution. — Transition Lime- 
stone. — Mr. M'Clure's Description of this Formation. — Mr. 
Featherstonhaugh's Old Red Sandstone. — Its Geological Dis- 
tribution 230 
CHAPTER XXIL 
GEOLOGY OF THE UNITED STATES. 
LOWER SECONDARY FORMATIONS. 
Carboniferous Group (De la Beche). Medial Order. 
Secondary Rocks— Their Division. — Carboniferous Limestone 
— Its Range. — Mr. Featherstonhaugh's Account of it. — The 
Coal Measures— Of what they consist— Their Situation.— 
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