CONTENTS xi 



PAGE 



Cumberlandite boulders 224 



Upper Cambrian quartzite pebbles 225 



Agates 225 



Chiastolite schist pebbles ........ 226 



Absence of kames and eskers . . . ... . . 226 



Post-glacial or recent deposits 226 



Freshwater swamps and peat bogs . . . . . . . 227 



Marine marshes . 227 



Wave and current action ......... 227 



Dunes and wind action .......... 228 



Black iron sand or magnetite . . . . . . . 229 



Great Salt Pond 229 



Economic geology ....... .... 230 



Bibliography of geology of Block Island 231 



Part III. Geology of Cape Cod and the Elizabeth Islands. By J. B. Woodworth 



Chapter I. — Geology of Cape Cod . 237 



Geography 237 



Location and area 237 



Topography 238 



Hydrography ............ 239 



Lakes and lakelets . . . 239 



Harbors and creeks 240 



Cartography .... . . . . . . . . . 242 



Descriptive geology 243 



Earlier reports 243 



The bed rock basement 247 



Pre-Pleistocene formations 248 



Pleistocene formations 248 



Pre-Wisconsin deposits 249 



Sankaty sand 249 



Jameco (?) gravel 252 



Gardiners (?) clay 255 



Jacob (?) sand 259 



Manhasset formation (?) . 259 



Herod gravel member (?) . . . . . . . 259 



Montauk till member (?) 259 



Hempstead gravel member (?) . . . . . . 260 



Summary .......... 260 



Vineyard interglacial stage 261 



Erosion phenomena. ........ 261 



Wellfleet plain 261 



Chatham plain .......... 262 



North Truro plain 263 



Wisconsin glacial deposits . .264 



Nantucket substage , . 264 



Falmouth substage . .269 



Falmouth moraine . .269 



The outwash plain . . 271 



