242 THE POPULAR SCIENCJ MONTHLY. 



Island, the widespread view of sea and land impresses itself 

 upon tlie observer, and in every way in which this range of 

 hills is brought to our notice we are unconsciously led to ap- 

 preciate the scenic importance of this legacy of the continental 

 ice sheet. 



From the scenery of Long Island Sound and the moraine one 

 may turn to that of the Hudson River. 



On the east shore of this noble stream is a terrace, pictur- 

 esquely dotted with handsome country seats, which extends al- 

 most continuously from New York to Peekskill, and, after a brief 

 interruj^tion where the steep slopes of Anthony's Nose and the 

 Dunderberg form the lower gate of the Highlands, reappears at 

 Garrison's and Cold Spring and forms the plain upon which the 

 Military Academy is located, at West Point, This terrace is 

 about seventy-five feet above tide at the Riverside Park in New 

 York city, and increases in height northward to about one hun- 

 dred and twenty feet at the State Camp near Peekskill and one 

 hundred and eighty feet at West Point. North of the High- 

 lands the remnants of terraces may be seen on both shores of the 

 river as far as Troy and throughout the valley of Lake Cham- 

 plain, increasing in height northward to the St. Lawrence River, 

 where, in the vicinity of Montreal, they have an altitude of over 

 five hundred feet. 



In these terraces is recorded ineffaceably the history of the 

 continental submergence previously mentioned. They are the 

 remnants of the deposit of sand and clay formed in the Hudson 

 and Champlain Valleys when submerged, and the surface of the 

 highest terrace indicates approximately the old sea level. 



These terraces, relics of Quaternary subsidence, are not, how- 

 ever, the only interesting geological phenomena to be seen along 

 the valley of the Hudson. The bold, precipitous Palisades, known 

 as widely as the river which they overlook, call our attention to 

 a period of volcanic activity in Mesozoic time. These lofty clifi^s 

 form the margin of a sheet of trap or igneous rock, three hundred 

 to four hundred feet in thickness, which was forced to the sur- 

 face in a molten state between the beds of red Triassic sandstone 

 which form the eastern border of northern New Jersey and of 

 Rockland County, New York. 



Throughout most of its extent the Palisade range has been 

 leveled off by wave action at some remote period of subsidence, 

 while immediately west and north of Nyack a portion which has 

 escaped erosion rises in high peaks with irregular outlines. 



Leaving the Palisades behind us, we enter the gorge of the 

 Highlands. The rocks which form these rugged steeps are of the 

 oldest and hardest in our State. Though they have yielded to the 

 cutting of the river current in past ages, they resist the degrad- 



