TABLE OF CONTENTS. 
XXV 
Page. 
Disturbance of strata since their deposition... 272 
Considerations on the equivalency and physical causes of this formation ..272 
1. Equivalency of this formation to Nevv-Jersey formation shown, viz, 
1. Lower strata similar. 272 
2. Lower strata similar underlie the marl deposits of New-Jersey.... 272 
3. Earthy green substances on Long island like New-Jersey marls.272 
4. Earthy green strata overlie the potter’s clay formation.273 
5. Fossils of Long island in geological position of marl fossils. ..273 
2, Physical causes of this formation...... 273 
Origin of materials from southwest... 273 
Disintegrating primary rocks. 273 
Cause of transport. 274 
Gulf stream in consequence of the dynamical laws regulating the equilibrium 
of the ocean. 274 
Reasons why marls and fossils do not abound on Long island. 274 
Cold polar current through Hudson valley would influence depositions by 
checked current and under current, and animal life by diminution of tem¬ 
perature ; and depositions of drift wood and plants by eddies.. 274 
Same causes have produced the same results in the country east of the Rocky 
mountains. 275 
2. Trappean DIVISION, geographical distribution in North-America. 278 
Range and extent in New-York of trap or greenstone. 278 
Mineralogical characters. 279 
Topographical and agricultural characters. 279 
Valleys across trap ranges ........ 280 
Elevation of high peaks. 280 
Long clove. 280 
Trend of the Hudson trap range. 280 
Short clove. 280 
Rockland lake. 280 
View from Verdrietige hook.280 
Trappean range re-appears on Staten island. 281 
Topographical features and height. 281 
Joints of the trap. 281 
Trap dykes, and sandstone altered by trap.... 281 
Semi-columnar and castellated forms near Nyack .. 281 
Enormous dykes or double faults. 282 
Lateral injections of trap between stiata. 282 
Rocks modifled by injections. 282 
Copper ores and micaceous oxide of iron. 282 
Agate. 282 
Columnar trap. 282 
