ERIE COUNTY. 187 
GEOLOGICAL STRUCTURE. 
The section of the rocks underlying Erie county is, in descending 
order, as follows: 
. Thickness. 
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MP NSECTOTOUSINA] Chassecore cece cioeckoceseleees uscueresuates ve Noselueiedsbe sees poceameseons We 
SOLE VeraMMSWALS Ret eacciceteh sce cisesesen seleelsd bees WeeaslcSeaecisacheusce bens 50-60 * 
AWE TV CNS VAG tereeeaye kaw ts saa wealectcisniesldteclesvekweasl sisaepue hase soe decene eoweestee sas 502) < 
MaMa UIMOM SN Chamsaeylocaccectaceeccen seestaesoed seek seloccecsiwesanswseeee seceeSedecsecs ROD. 
GMM TINT OMe MIMESTOM Cease tnesssts was ceciescecscea suececioesecelscecasuseseclecceeees OQ) 
HAAS OLMIMETOUSWITMN CSLONE itacaferecccece:scecsuces soecdelcedoss coectesescccs sciences 100 ? 
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QURAN UCC CTOMOUPceccdstectes iscsi cocebetscmoctlectscsacdecescsctevserdtveccsssee Oe © 
10. Onondaga salt group ..... aM eck da'ekesiee Uaicdieh ats bashed rene ace Ne wee Beate nas se 30-40 “ 
In the oil well bored at the mouth of the Vermilion river, the Niagara 
limestone, the Clinton group, and Medina sandstone were penetrated, 
but they nowhere come to the surface within the limits of the county. 
Of the foregoing strata, the first is the sandstone quarried at Amherst 
and Brownhelm, of which the outcrop crosses the east line of the county 
within less than a half mile of the lake shore; thence it sweeps round 
to the south and west, passing through Berlinville, and a little east of 
Norwalk, in Huron county. Within the area lying to the south and east 
of this line the Berea grit underlies most of the surface, but it is very 
generally covered and concealed by the Drift materials; and it is only 
where its more compact and massive portions have resisted the action of 
erosive agents, and these have been left in relief, that it projects above 
the surface. The hills in which the Amherst and Brownhelm quarries 
are located, and the elevation known as Berlin Heights, are all masses of 
this character. They were once blufis upon the shore of the Lake, and 
every where show marks of the action of water and ice. Along the out- 
crop of the Berea grit its softer portions have undoubtedly been most ex- 
tensively eroded, and are now deeply covered by Drift deposits, so that 
probably little of this portion of the area it occupies will furnish valu- 
able quarries of building stone; but as the surface rises and the rocks 
dip toward the south and east it soon passes below the surface, and there 
is every probability that within the townships of Berlinville, Lawrence, 
and Vermilion, the Berea grit will hereafter be quarried in many local- 
ities precisely as it now is at Berea. 
So far as we can judge from the exposures of this rock in Hrie and 
Huron counties, it becomes more shaly toward the south, passing gradu- 
ally into the soft ochery sandstone which represents it at Ashland, Mans- 
field, and further south. 
