Handbook of Paleontology 243 



dam. Warping and differential uplift followed the Little 

 Falls deposition, causing the retreat of shore lines fol- 

 lowed by erosion resulting in the unconformity at the top 

 of the Little Falls. 



The Wappinger terrane comprises a large development 

 of dolomitic limestone with a total thickness of approx- 

 imately 1000 feet, and is termed a terrane because several 

 fossil zones have been recognized representing the Lower 

 Cambrian, the Potsdam and Hoyt horizons in the Ozark- 

 ian system and the Beekmantown and lower Trenton in 

 the Canadian and Ordovician systems respectively. That 

 is, this development of limestones consists of several 

 members separated by gaps in deposition. These lime- 

 stones occur in Dutchess, Orange and Ulster counties and 

 have also been traced into Columbia county. The beds 

 lie above the Poughquag quartzite and below the "Hud- 

 son river" slates. The Wappinger limestone received its 

 name from its occurrence along Wappinger creek in 

 Dutchess county (Dana, Dwight '79). It is a compact, 

 massively bedded, dolomitic limestone of three types: 



( 1 ) a light gray, fine-grained variety, the prevailing type ; 



(2) a darker bluish gray, coarsely crystalline variety; 



(3) a crystalline conglomerate. In practically all out- 

 crops the limestone is conspicuous for its brecciated char- 

 acter due to the fractured nature of the rock. The pre- 

 vailing light gray, fine-textured limestone has been gen- 

 erally considered of Beekmantown (Canadian) age; the 

 dark bluish gray, coarsely crystalline limestone contains 

 fossils of Trenton (Ordovician) age. The conglomeratic 

 limestone marks the break between the Beekmantown be- 

 low and the Trenton above. A study of its fossils indi- 

 cates that the break marks the time immediately preced- 



