PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 27 



The Heuvelton formation consists of white, vitreous sandstone 

 often with a decided platy structure and much ripple-marking and 

 minor cross-bedding. In stream beds the surface of the rock is 

 usually strongly stained with reddish brown iron rust or is even 

 nearly black, and the lamination is clearly brought out; but the 

 glaciated ledges commonly show the rock in about three heavy 

 benches of glistening whiteness. The cement is clearly silicious, 

 with the original sand grains fine and uniform, so that these polished 

 surfaces are nearly indestructible and essentially a quartzite. Very 

 rarely there is a small lentil or even a thin stratum of slightly cal- 

 careous material. At Sissonville especially (locality 31) the number 

 and liminess of such lentils is more marked than to the westward. 

 This sandstone may, therefore, become less pronounced eastward 

 of our area. Yet at Norwood the masses thrown out in construct- 

 ing the concrete dam (locality 19)^ indicate no loss of strength at 

 this point, and the full thickness of 20 feet is said to have been 

 encountered ; also that it was an exceedingly difhcult rock to drill 

 on account of its flintiness. 



Unlike the formations below, the Heuvelton is fossiliferous, 

 though its fossils are poorly preserved as in general with our for- 

 mations. . A large, flatly coiled shell not unlike the Eccyliopterus 

 types of the Beekmantown (Ogdensburg) and sometimes reaching 

 a diameter of three and one-half inches, occurs sparingly, especially 

 near the summit. Doctor Ulrich suggests that this species may pos- 

 sibly be Helicotoma uniangulata,^ '' w^hich is char- 

 acteristic of the Chepultepec (upper) series of the Ozarkian." It 

 is possible, however, that more than one form is represented by the 

 crude molds that have been seen. 



Besides the shells, a characteristic burrowlike or fucoidal struc- 

 ture is oftentimes pronounced. This consists of tubular windings, 

 about the size of a slate pencil, and filled with either the same 

 white or a bluish sand, or rarely weathering more rusty. They 

 penetrate the strata at all angles, and by a tendency to radiate in 

 twos or threes from a center frequently give to the weathered 

 surfaces the appearance of being covered with turkey tracks. This 



^The new dam is situated about 25 rods farther up the stream than the 

 dam shown on the map, in line with the end of the street on the east 

 side of the river. 



^Euomphalus uniangulatus Hall, Paleontologj^ of N. Y. 1:9; 

 pi. 13, fig. I, la. There is a very fine specimen of this species in the col- 

 lection of St Lawrence University, besides some poorer ones, all in loose 

 rotten rock of 'the glacial drift; but these are evidently out of the succeed- 

 ing Bucks Bridge formation. 



