346 THE CAMBRIAN. [bull. 81. 



Section at Saratoga. — The section, as determined north and west of 

 Saratoga Springs, and north as far as Ooiinth, New York, has, at the 

 base, about 200 feet of evenly bedded, compact, grayish to yellowish 

 colored sandstone, that rests unconformably against or upon spurs or 

 ridges of pre-Cambrian gneiss. Including the upper beds of sand- 

 stone, the section 3 miles north of Saratoga village gives in ascending 

 order : 



• Feet. 



(1) Sandstone 40 



(2) Oolitic limestone 30 



(3) Dark gray, evenly bedded limestone 50 



(4) Unfossiliferous, impure, compact, more or less siliceous lime- 



stoue : 95 



(5) Massive-bedded, slightly magnesian, gray and dove colored 



limestones with numerous small, narrow-chambered cephal- 



opods near the summit 35 



(6) Massive layers of steel-gray, more or less arenaceous lime- 



stone 125 



(7) Bird's-eye limestone 6 



(8) Black River limestone 4 



(9) Trenton limestone 40 



The limestone (2, 3) capping the sandstone (1) of the section is also found at 

 Whitehall and at Comstock's Landing, Washington County, New York, where it has 

 been, as was the limestone (2, 3), referred to the Calciferous. The limestone 2 aud 3 

 appears to have been/on the southwestern side of the Adirondack Mountains, the 

 closing deposit of the Cambrian; and there is but little doubt that if we could find 

 a fauna in the limestone (4) of the section it would serve to connect the Cambrian 

 and Lower Silurian (Ordovician) faunas. 1 



The following fauna was found in No. 3 of the section : 



Cryptozoa proliferum. Billingsia saratogensis. 



Lingulepis acuminata. Matthevia variabilis. 



Platycerasininutissimum. Dikelocephalus hartti. 



hoyti. speciosus. 



Metoptoma cornutiforme. Ptychoparia calcifera. 



simplex. (A.) saratogensis. 



The comparison of the Chateaugay Chasm section with that of Sara- 

 toga County proves very clearly by the included faunas that the Pots- 

 dam epoch closed on the south side of the Adirondacks with a deposit 

 of limestone carrying the Dikelocephalus fauna. It is found in the 

 upper beds of the quartzite on Marble River in the township of Cha- 

 teaugay, and in each section the Calciferous formation is superjacent to 

 the closing epoch of the Potsdam. 



The greatest depth reached in the formation is that of the section of 

 Hemmingford Mountain. Unfortunately this section has not been 

 studied so as to determine whether there is any fauna present in the 

 sandstones. The section at Au Sable Chasm, however, shows that a sec- 

 ond horizon of the Upper Cambrian fauna occurs about the Adiron- 

 dacks. This is the zone of Ptychoparia minnta, corresponding to the 

 zone of Ptychoparia minor of the Wisconsin section. 



1 Second contribution to the studies of the Cambrian faunas of North America. U. S. Geol. Survey 

 Bull. No. 30, 1886, p. 22. 



