Handbook of Paleontology 333 



ioxus, Dalmanites limulurus, Homalonoius delphinoce- 

 phalus, Arctinurns (Lichas) boltoni). 



The Shawangunk conglomerate (Mather MO) is the 

 basal formation in eastern New York. On the basis of 

 the eurypterids found at Otisville, N. Y., in the thin 

 beds of dark shales intercalated in the grit, together with 

 other considerations, not faunal, this conglomerate was 

 regarded as of the age of the Pitts ford and the basal 

 member of the Salina in the east (Clarke and Ruede- 

 mann '07, '12 ; Hartnagel '07). Later this formation was 

 placed in the Medina (Van Ingen '11; Schuchert T6) 

 because the then supposed Medina fossil, Arthrophycus 

 alleghaniensis, was found at Otisville in the midst of the 

 eurypterid beds ; but the upper pink and reddish zones 

 were considered of Clinton age and equivalent to the 

 iron ore zones. Van Ingen (Tl) considered it of 

 Medina-Clinton-Niagara age. The latest view is that this 

 basal Silurian deposit began earlier in Pennsylvania, and 

 that as it overlaps northward upon the old land surface, 

 its base is made by younger and younger beds so that in 

 New York State the Shawangunk is mainly or entirely 

 of Clinton age or younger (Ulrich). The Shawangunk 

 conglomerate decreases in thickness northwardly from 

 the Shawangunk mountains from which it takes its name 

 and in which it reaches a thickness of 600 feet or more. 

 It is gray to whitish, sometimes slightly greenish in color, 

 and consists of conglomerates, grits and shales. It rests 

 unconformable* upon the Ordovician beneath and out- 

 crops in the Kingston-Port Jervis area and in Orange 

 county. Its occurrence in the latter area is the continua- 

 tion of the Green Pond conglomerate of New Jersey. 

 The shale partings of the Shawangunk are usually of in- 

 significant thickness ; in general the formation tends to 



