TABULATION OF THE FORMATIONS. 



Formations exposed ht Chazy Township. 



287 



Formation. 



Character. 

 t 



Thickness. 



Trenton 



Black, slaty limestone, hijjhly 

 fossiliferous at certain hori- 

 zons. 



Unknown in the Lake Cham- 

 plain reirion, hut clearly sev- 

 eral hundred feet at least. 



l)huk Kiver. 



Chazy 



Calciferous 



Black, slaty limestone, more 

 massive than the overlying 

 Ti-enton ; sparinizly fossilifer- 

 ons, but with a characteristic 

 fauna. 



From r)0 to 50 feet. 



^lassive beds of limestone, the 

 whole separable into a lower, 

 a middle and an upper divis- 

 ion, each well marked litho- 

 loLjicallv and j)aleontologic- 

 ally.* 



About 750 feet. The lower, 

 nuddle and upper divisions 

 have a thickness of 850, 250 

 and 150 feet respectively.* 



Ma.'jsive, fj:ray, siliceous lime- Not known for this vicinity. At 

 stones and dolonutes, which j the head of lake Champlain 

 are si)aringlv fossiliferous. the formation has a measured 



thicknessof 1,800 feet, t 



Potsdam ..... Ma.ssive beds of sandstone, of 

 red, white or yellow-brown 

 color and varying degree of 

 in<lunition, with conglomer- 

 ate and arkose at the base, 

 and jnissage-bcds to the Cal- 

 ciferous at the summit. 



Unknown, but at least several 

 hundred feet. Mr Walcott has 

 measured sections of 250 and 

 .350 feet respectively at Cha- 

 teaugay chasm and Ausal)le 

 chasm, which represent mere- 

 ly unknown portions of the 

 whole, i 



The Faults. 



THEIR PREVALENCE ly THE REGION. 



Wherever any bit of the region bordering on lake Chani[)lain has l)een 

 mapped in detail one or more faults have been disch^sed. Sometimes 

 the faultdine itself is shown in section, but more commonly its i)resence 

 is indicated by the structure merely. The num])er of faults already 

 mentioned or mapped in tlie n.'gion must ))e 20 or o(), yet they i)robably 

 represent only a small proportion of tho.se which exist. While faults 



• Hratnard and Seeley : Am. GeoloKiRt, November, 1888, p. .124. 



t Hruinard and .Seeley: Bull. Am. Muh. Nat. Hist., vol. iii, no. 1, p. 2. 



J C. D. Walcott: Bull. U. 8. Geol. Survey, no. 81, pp. 3«;j. .$»♦. 



