196 CONTENTS 



' Page 



III. Descriptive notes of quarry districts and quarries. . 228-281 



I. Crystalline rocks 228-255 



GraniteS;, etc - 228-234 



Limestones and marbles 234-255 



Marbles 234-238 



Limestones 238-255 



Hudson-Champlain valley 238-243 



Mohawk valley 243-246 



St. Lawrence valley 247-248 



Lower and Upper Helderberg groups. . . . 249-254 



Niagara limestone 254-255 



II. Fragmental rocks — sandstones 255-281 



Potsdam sandstone 255-258 



Hudson river group 259-260 



Medina epoch 260-265 



Hamilton and Portage groups 265-275 



Hudson river blue-stone ». « 265-271 



Sandstone of the Clinton group 273 



Portage group (western) 274-275 



Chemung group 275-278 



Triassic or new red sandstone 278 



Slate 279-281 



IV. On the use of stone in cities o 282-352 



V. Physical tests and chemical examinations of build- 

 ing stone 353~37^ 



VI. On the durability of building stone and causes of 



DECAY 373~3^9 



Physical structure = 373~377 



Chemical composition 377~379 



Accident of position 379~38i 



Causes of decay 382-389 



Index 391-395 



Map , 396 



