The geological formations are very ancient, consisting mainly of micaceous gneiss or granite, * the former largely preponderating, the exposed surfaces indicatingsubjectionto intense heatand pressure, with so great displacement that the strata are nearly vertical, outcropping in numerous parallel ledges, not continuous, but cii echelon, and giving steep inclination to hillsides. A coarse, crystallized limestone" of varying hardness, ranging about north-northeast, crops out at King's Bridge and on the Whiting and Delafield estates, Spuyten Duyvil Ridge. On the latter ridge the surface of the primary rocks is strewn with trap boulders.

DiscovEKY. -- The earliest known visitor to this locality was Henry Hudson. Going up the river which bears his name, he skirted its westerly shore September 13, 1609, and, on his return, was attacked, Oc-

' So called after George Tippett, an early settler and proprietor, and of late corrupted into Tibbilt'e Brook. Its Indian name was Jloshohi. It has also been known as Mill Creek and Yonkers Hirer.

■-The highest ground within the limits of New York City. The elevation of Fort W'ashington, the greatest on Manhattan Island, is two hundred and sixty-four feet.

3 So called after Jonas Bronck, the earliest white settler and proprietor of "Bronck's Land," now Morriaania, Twenty-third Ward, New York.

'.\n arliticial pond, formed by Jacobus Van Cortlandt, circum 1700, by damming Tippett's Brook.

5.\ffording building-stone of fine quality. Before 1750 quarries of "broken stone " were worked on Spuyten Duyvil Ridge, the whole extent of which is scarred by them. The large quarries at Spuyten Duyvil Point were worked until about IS.'iO.