TABLE OF CONTENTS. XV 



Location with respect to transportation routes 305 



Location with respect to fuel supplies 305 



Location with respect to markets 306 



CHAPTER XXIII. 



LIMESTONES. 



Limestones in general 307 



Varieties and origin 307 



Composition of limestones 308 



Impurities of limestones. 309 



Physical characters 310 



Effects of heating 311 



Pure hard limestones 312 



Use in cement manufacture 312 



Composition of hard limestones actually used 312 



Prospecting and examining limestone deposits 315 



Preliminary examination 316 



Detailed mapping and sampling 317 



Chalk and other soft limestones 318 



Origin of chalk 318 



Distribution of chalk in the United States 319 



Physical properties 320 



Composition of chalk and soft limestones actually used 320 



Examining chalk deposits 321 



List of references on chalks and soft limestones 322 



CHAPTER XXIV. 



ARGILLACEOUS LIMESTONE: CEMENT ROCK. 



Definition 323 



"Cement rock" of the Lehigh district 324 



Geology of the district 324 



Character and composition of the "cement rock" 328 



Quarry practice in the Lehigh district 329 



Cement production of the district 331 



Probable extension of the district 331 



"Cement rock" in other states 332 



Analyses of western "cement rocks" 333 



List of references on " cement rock" 333 



CHAPTER XXV. 



FRESH-WATER MARLS. 



Various uses of the term " marl " 334 



Occurrence of marl deposits 335 



