108 WALKS AND TALKS. 



the flow of springs, and the discharge of oil or gas from 

 natural or artificial openings. Many springs and wells show 

 a daily periodicity in the volume of the flow, corresponding 

 with the diurnal variations in the pressure and temperature of 

 the atmosphere. Such facts increase the presumption that 

 lunar and solar tidal actions may affect the flow of molten 

 matter, and also the distribution of stresses and movements in 

 the earth's crust. 



. THE KRANIEWORKOKTHE MOUNTAINS. 



MOUNTAIN STRUCTURES. 



LET us imagine ourselves standing on the bald summit 

 of Mount Marcy. This is the highest peak of the Adirondacks. 

 It rises 5,400 feet above sea-level. Beneath us, on every side, 

 spreads a wilderness of mountain swells and intervening 

 wooded valleys. In the dim and smoky horizon, in some direc- 

 tions, we glimpse the indications of white villages and smoking 

 chimneys, and crawling locomotives, and navigated waters ; 

 but the aspect, on the whole, is one not suggested by the knowl- 

 edge that we stand in the Empire State with its five millions 

 of citizens. Here nature still rules in one of her wildest moods. 



Notice the forms of these summits. How symmetrically 

 the contour sweeps from the lower and flatter slopes upward. 

 How gracefully these mountain swellings dissolve in the green 

 ground of the landscape beneath. Look at our feet ; the 

 naked rock lies cracked and weathered by the frosts of un- 

 numbered Winters. The chips of the mountain strew the 

 cone for eight hundred feet below. There the mountain firs, 

 shrinking from the weather, begin to appear, but only as 

 prostrate, crawling, and stunted shrubs. These rocks are 

 Eozoic. How hard and crystalline and stubborn they look. 

 These black crystals are pyroxene; the dark, dusky ones are 

 a species of feldspar called labrad&rite. The mixture forms a 

 rock known as Norite. Polished surfaces present a highly 

 pleasing appearance. This rock forms all the central mass of 



