18 ANNUAL REPORT 
GEOLOGY OF THE COUNTY. 
The surface rocks in the western part of the cotinty belong to the 
Niagara; those near the middle to the Lower Helderberg; and those 
farther east to the Corniferous limestone and the Ohio shales. By far the 
greater part of the producing territory has the Niagara for the surface 
formation. The topography resembles that of the adjacent counties on 
the west; it is flat on the west and northwest sides, rolling in the middle 
and eastern parts. A beach of ancient Lake Erie crosses the county 
from the southwest to the northeast, and is the most striking feature of 
the surface geology of the county. 
The succession of strata underground corresponds very closely with 
that in the counties west and north, and consequently will not be repeated 
here. The Trenton limestone in the northwestern corner of the county 
is part of the nearly flat dome, that forms so striking a feature of the oil 
territory in that part of the state. Its position is about 475 feet below 
tide level. From this corner the rock dips east and south, at Tiffin being 
765 feet, and at Attica, on the east side of the county, about 1,130 feet 
below sea level. At Tiffin a small fold is found; well No. 1 drilled near 
the north of Rock creek, found the Trenton at 1,490 feet, while No. 2 — 
drilled about one mile to the west, did not reach that formation until a 
depth of 1,610 feet was reached. The latter well stands on higher ground, 
but not sufficient to account for the increased depth of the Trenton. The 
boundaries and direction of extent of the arch have not been determined, 
but the productive territory indicates that it is crescent shaped, with the 
convex side turned to the west. In other respects the geology of the 
county is similar to that of Sandusky and Hancock, and the facts that 
have been stated for those counties will not be restated here. 
ALLEN COUNTY. 
The oil territory in Hancock county extends southwest into Allen, 
where it makes it first appearance in Richland township. It continues 
southwest across the county as a series of disconnected but closely related 
pools, and then enters Auglaize county. In the western part of Allen two 
large pools are found, and one of these extends westward into Van Wert 
county. Besides these pools there are several small ones. These points 
will be made clear in the following discussion by townships: 
Ottawa Township.-This is coextensive with the Lima city limits. The 
first well was drilled in 1885, and work became active one year later. By 
April 1, 1886, fourteen wells had been completed; by July 1, fifty-seven, 
and by November 1, one hundred and sixty-five. The production by 
months was as follows: 
