GeoFacts No. 23 OHIO DEPARTMENT OF NATURAL RESOURCES • DIVISION OF GEOLOGICAL SURVEY
A BRIEF SUMMARY OF THE GEOLOGIC HISTORY OF OHIO
GEOLOGIC PERIOD1 SETTING LIFE FORMS ROCK TYPES ECONOMIC PRODUCTS (million years ago)
Quaternary Two-thirds of Ohio was covered • many large mammals • glacial till, clay, silt, sand, • common clay products (clay) 2.6 mya–Present by mile-thick ice during glacial such as mastodons, gravel • material for road construction periods. mammoths, giant bea- • form the surface sedi- and cement (sand, gravel) vers, and ground sloths, ments in northern and • Sand and gravel are also im- as well as modern plants western Ohio portant aquifers and animals, including humans
Mesozoic & Tertiary Ohio was above sea level, and • no known record, but 251–2.6 mya weathering erosion and nonde- dinosaurs probably position prevailed. roamed Ohio during the Mesozoic
Permian During early Permian time, • sparse freshwater fossils • sandstone, shale, fresh- • crushed stone (limestone) 299–251 mya southeastern Ohio was a coastal- such as snails, clams, water limestone, coal • electric power (coal) plain swamp. Ohio lay about 5° fi shes • form the surface rocks in north of the Equator. The swamp • marine fossils rare southeasternmost Ohio eventually was fi lled by infl ux • sparse land fossils in- of deltaic sand and mud. Later clude plants, amphib- Permian time was characterized ians, reptiles by uplift and erosion.
Pennsylvanian Ohio in Pennsylvanian time was • land plants abundant • sandstone, conglomer- • building stone, crushed stone 318–299 mya a relatively flat coastal-plain • terrestrial and freshwa- ate, shale, clay, limestone, for construction and industrial swamp in equatorial latitudes. ter life included amphib- coal, fl int, ironstone uses such as glass manufactur- Fluctuations in sea level resulted ians, reptiles, freshwater • form the surface rocks in ing, oil and gas (sandstone) in alternating terrestrial, freshwa- clams eastern Ohio • crushed stone for construction ter, and marine deposits. • marine life included and cement (limestone) crinoids, snails, cepha- • pottery and common clay lopods, brachiopods, products (shale, clay) fi shes • electric power (coal) • trilobites rare • during the 1800s Ohio was a major iron-producing state
Mississippian During latest Devonian and early • brachiopods, clams, cri- • sandstone, siltstone, • building stone, crushed stone 359–318 mya Mississippian time, dark organic noids, fi shes conglomerate, shale, for construction and industrial muds gave way to fl uvial and • land plants increasingly limestone uses, oil and gas (sandstone) deltaic silts and sands. Ohio lay in abundant • form the surface rocks in • crushed stone for construction equatorial latitudes. During late northwestern and east- and cement (limestone) Mississippian time, a shallow sea central Ohio • common clay products (shale) deposited limy sediments. Dur- • Ohio has been a major producer ing latest Mississippian time the of building stone from the Mis- seas retreated, leaving a sparse sissippian Berea Sandstone for rock record. over 150 years
Devonian Most of Ohio was dry land during • coral reefs, bryozoans, • limestone, dolomite, • crushed stone for construction 416–359 mya early Devonian time, although brachiopods, trilobites, shale, sandstone and cement, aglime (limestone the sea still covered eastern Ohio. cephalopods, clams, cri- • form the surface rocks & dolomite) Ohio was in equatorial latitudes. noids, ostracodes in northwestern Ohio, • synfuels and natural gas (shale, During Middle Devonian time, • fi rst major appearance of through central Ohio, sandstone, limestone) warm, shallow seas deposited sharks and bony fi shes and along the Lake Erie limy sediments. Layers of muddy during Middle Devonian shore sediments and some volcanic ash • true land plants appear during late Middle Devonian time signaled renewed volcanic activity and mountain building east of Ohio. During late Devo- nian time, the Ohio sea became stagnant; circulation was poor, and the water was generally anoxic (lacking oxygen). Thick layers of black, organic-rich, uranium-bearing mud were de- posited in these “stinking seas.” continued ➮ 4.6 billion–542mya Precambrian 542–488 mya Cambrian 488–443 mya Ordovician 443–416 mya Silurian
STATE OHIO DEPARTMENT DIVISION OF recycled OF OHIO OF NATURAL RESOURCES GEOLOGICAL SURVEY paper