DETAILED RECORDS. 249 
1271. Well near Genoa, Ottawa County. 
[Well begun and completed in October, 1905. Authority, E. L. Rugh, of Rugh & Delo, contractors. 
Samples preserved. Geologic correlations by S. Sanford.] 
Oil is found in the Trenton limestone (Ordovician). The overlying formations are, in 
downward order, Helderberg limestone, Niagara limestone and shale, Clinton limestone, 
and Medina shale (Silurian); and Cincinnati (gray) and Utica (brown) shales (Qrdovician). 
Record of well 2 miles north of Genoa. 
Helderberg, Niagara, and Clinton: Feet. 
Hard gray magnesian limestone 25- 210 
Soft white limestone 210- 390 
Hard blue-gray limestone 390- 445 
Soft gray shale - 445- 520 
Soft light-gray shaly limestone 520- 570 
Soft gray dolomite. 570 (300 
Medina: 
Soft red shale 600- 690 
Cincinnati : 
Hard gray shale 690- 800 
Soft gray shale 800-1, 075 
Utica: 
Hard dark brownish-gray shale 1, 075-1, 299 
Trenton : 
Hard brown and gray limestone with light and dark gray shale from 1,314 
to 1,325 feet 1, 299-1, 351 
Rig used, cable. Diameter of casing, 10 inches from to 25 feet: 8 inches from 25 to 
520 feet. We'll shot with 240 quarts of nitroglycerin. Initial yield of oil, 70 barrels in 
twenty-four hours; gravity, 34° B. 
1281. Well near Helena, Sandusky County. 
[Well begun July 13, 1905; completed August 1, 1905. Authority, O. J. Gam, of Imler, Garn & Co., 
owners. Incomplete set of samples preserved. Geologic correlations by S. Sanford.] 
Helena is near the eastern edge of an irregular oil pool that underlies parts of Sandusky, 
Wood, and Seneca counties. The oil occurs in the Trenton limestone. The overlying 
formations below the drift are, in downward order, Niagara limestone and shale, Clinton 
shale, and Medina shale (Silurian); Cincinnati shale and limestone, Utica shale, and Tren- 
ton limestone (Ordovician). 
Record of well in the SW. ^ NE. \ sec. 35, Washington Tovmship. 
Drift: Feet. 
Yellow sand and' clay 0- 7 
Niagara : 
Soft white limestone 7- 40 
Limestone with blue slate (gray sandstone) 40- 60 
Very hard white (to brownish cherty) limestone. 60- 90 
Hard white (to brownish cherty magnesian) limestone 90-130 
Gray limestone (brownish, magnesian) 130-170 
Soft, pasty white (and gray magnesian) limestone 170-210 
Hard light-gray (magnesian) limestone 210-220 
Hard gray limestone and dark-gray shale 220-230 
Hard blue limestone (dark-gray limy shale) 230-250 
Hard white limestone (magnesian) 250-270 
Hard blue limestone (light and dark gray) 270-290 
