SILURIC SECTION, ROCHESTER TO LAKE HURON 307 



Lockport, New York, section (15 miles luest of Medina). — The se- 

 quence here is difficult to make out because of the disconnected local sec- 

 tions. A visit in August, 1913, revealed the following: 



Lockport dolomite. Thickness about 150 feet. 



Gasport limestone meuiher (Kindle, 1918), about as at Niagara gorge. 

 De Cew memher (Williams MS., 1914). At the head of the "Gulf" near 

 the brick-paved north-south road may be seen the basal beds. They 

 are essentially like those in the Niagara gorge, with the upper contact 

 line much more irregular than the lower one, which is fairly even 

 with the Rochester shale. Thickness about 5 feet. 



Irregular wavy contact. Time break, if any, short. 



Rochester shale. About 60 feet thick. About as at Niagara gorge. 



Clinton formation. About 30 feet thick, and as at Niagara gorge. 



Disconformity. Sodus shale absent. [Grabau as censor questions the break 

 here. He says it is another case of lateral change.] 



Medina formation. Thickness about 53 feet without the basal sandstone, with 

 it 70 feet. This formation was studied back of the United Indurated 

 Pipe Co., along the stream, on the opposite bank, and finally in White- 

 more quarries. The Medina is here essentially a very shallow water 

 deposit with occasional preservation of the strand-line, or nearly so. 

 "Gray band," a white fine-grained sandstone, 2 feet thick. 

 Dark red thin-bedded sandstones and red sandy shales, 10 feet thick. 

 Arthrophycus allcghaiiiense occurs at the very top and probably also 

 throughout the entire zone. 

 Local zones of Dwdalus archimedes (the type locality for this fossil). 

 Here in two beds with a combined thickness of 2.5 feet. In one hori- 

 zontal direction these burrows were seen to vanish within 500 feet. 

 Red sandy shales, thin ferruginous mud bands, and red and white sand- 

 stones, with an estimated thickness of 30 feet. It is in the upper 20 

 feet that the Whitemore quarries are located, from which, in the red 

 and ferruginous layers near the top of the quarry, the bulk of the 

 Medina fauna of Lockport has been derived. From this zone and 

 place Hall described Rhynchotreta (?) plicata, Whitfieldella ohlata, 

 Pleurotomaria (?) Utorea, Murchisonia (?) conoidea, Oncoceras gih- 

 hosum. and Orthocnas iiiultiseptuui. The red sandstones are often 

 replete with intraformational red shale pebble conglomerates in layers 

 up to 4 inches thick. Some of the white sandstones abound in Lingula 

 cuneata. and some of the layers have smooth beach-washed surfaces 

 with stranded Lingulas, proving the shore conditions of deposition. 

 The sandstones are a series of shallow lenses laid down in red muds. 

 Light greenish sandy shales alternating with thin sandstones, with an 



estimated thickness of 10 feet. No fossils were seen. 

 Basal white sandstone, 17 feet thick. The upper 11 feet are thin-bedded, 

 while the lower 6 feet are massive. The under surface fills in the 

 siin-cracked furrows of the Queenston below. May be equivalent to 

 the Whirlpool sandstone. 



Disconformity. Base of Siluric. 



Queenston. Top of Ordovicic (Richmondian). Four feet of this formation 

 may be seen above the canal leading to the turbine of the Pipe Co. 



