CONTENTS. 



PART II. 



CHAPTER XJX. 

 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 Systenn. — 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 OF THE UNITED STATES. 



Primitive Rocks. — Prof. Hitchcock's Arrangement. — Stratified 

 and Unstratified. — Distrihution 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 XXH. 

 GEOLOGY OF THE UNITED STATES. 



LOWER SECONDARY FORMATIONS. 



Carbmiferous 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. — 



