No. 9. — On the Relations of tJie Triassic Traps and Sandstones of 



the Eastern United States. By William Morris Davis. 



1. Introductory. 



2. Literature. 



3. Observations. Nomenclature. — A, Turner's Falls. — B, Mount Tom. — C, 



West SpringMd, Mass. — D, Beckley Station. ~ E, Mcriden. — F, Walling- 

 ford. — G, New Haven, Conn. — II, Fort Lee and Englewood, — J, Weohawken, 

 — K, Jersey City. — L, Paterson and Little Falls. — M, Feltville. — N, Mar- 

 tin's Dock. — 0. Point Pleasant Station. — P, Lambert ville, K. J. 



4. Brief Statement oe Former Views. 



5. General Discussion. Origin of the Triassic Estuaries and Cause of Trap Erup- 



tions ; Origin and Deposition of the Strata ; Composition of the Trap ; Kelations 

 of the Trap and Sandstone ; Eeview of Previous Ideas ; Test-Characters for In- 

 truded and Overflow Sheets ; Examples of these elsewhere; Dikes; Intrusions; 

 Overflows; Amygdaloida; Elfect of Trap on Sandstones; Tilting; Theories to 

 account for the Monoclinal Structure ; Faults ; Folds. 



6. Summary, 



1. INTRODUCTORY. 



Since seeing in 1877 the trap conglomerate on the back of Mount 

 Tom, I have doubted the generally accepted explanation of the intrusive 

 orighi of the Triassic traps, and inclined to Hitchcock's theory of their 

 origin by overflow contemporaneous with the deposit of the sandstone. 

 During the past summer the desired opportunity came to examine the 

 question further, by personal observation, in Massachusetts, Connecticut, 

 and New Jersey, as detailed below, and with the result of satisfying my- 

 self that both views are correct; that some of the trap sheets are of 

 intrusive, and some of overflow origin. The Palisade range along the 

 Hudson may be taken as the type of the first, as has been shown by 

 Rusaell ; Mount Tom in Massachusetts represents the second, as was 

 shown by Hitchcock. Other examples will be found below. 



My endeavor has been to discover critical points that give decisive 

 evidence one way or the other as to the origin of the trap sheets, so as 

 to compel instead of merely allowing an explanation ; but observations 

 satisfactory or compulsory to one observer arc not always so to another, 

 and I cannot, therefore, expect that wliat has convinced me will surely 



VOL. VII. — no. 9. 



