An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous...
Transcript of An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous...
![Page 1: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/1.jpg)
An Introduction to the Geology of Virginia
Matt Heller
![Page 2: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/2.jpg)
Topics to cover:
Physiography (physical geography)
Geology – by province
Why is geology important?
![Page 3: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/3.jpg)
It creates topography
It makes soil
It channels water
Geology + Climate = Ecology
Why is geology important?
![Page 4: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/4.jpg)
Northern hardpan basic oak-hickory forest
![Page 5: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/5.jpg)
Geology influences human activity
Why is geology important?
Transportation
Hobbies
Commerce
Industry
Population
Land use
![Page 6: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/6.jpg)
![Page 7: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/7.jpg)
![Page 8: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/8.jpg)
Geology – Limestone
![Page 9: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/9.jpg)
Geology – Black shale
![Page 10: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/10.jpg)
The Virginia physiographic provinces you may have learned in school!
Chuck Bailey, College of William and Mary
![Page 11: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/11.jpg)
...a more detailed look at these provinces
Acknowledgement to Chuck Bailey, William and Mary
![Page 12: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/12.jpg)
Virginia’s physiography is controlled by geology
![Page 13: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/13.jpg)
Unconsolidated Sediments
Crystalline metamorphic and igneous
rocks
Sedimentary Rocks
Appalachian Plateau
Blue Ridge Coastal Plain
Valley and Ridge Mesozoic Basins
Piedmont
We use the same province names for geologic provinces
![Page 14: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/14.jpg)
Valley and Ridge Carbonate and clastic sedimentary rocks (limestone, dolomite, shale, sandstone, chert) with rare igneous rocks (mostly basalt). Age: Paleozoic (320 - 550 Ma)
-mostly marine (below sea level) -steep dips, tight folds, and faults are common. -fossiliferous -rare coal in youngest part of section.
![Page 15: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/15.jpg)
Vertical beds of limestone and dolomite, Elkton
![Page 16: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/16.jpg)
Rainbow gap, near Clifton Forge
Fold in Martinsburg Formation, near Shenandoah
![Page 17: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/17.jpg)
Fault breccia along Pulaski fault, near Marion
![Page 18: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/18.jpg)
Appalachian Plateau Mostly clastic sedimentary rocks (shale, sandstone, and siltstone, with lesser limestone and coal).
Age: Late Paleozoic (290 - 320 Ma)
-mostly terrestrial (above sea level). -gentle dips and broad folds are common. -fossiliferous, may contain coal beds.
![Page 19: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/19.jpg)
![Page 20: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/20.jpg)
Red colored beds are normally associated with terrestrial deposits
![Page 21: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/21.jpg)
Mesozoic Basins Clastic sedimentary rocks (sandstone, conglomerate, siltstone, shale, coal). Igneous rocks (basalt) Age: Mesozoic (200 - 225 Ma)
Rocks are commonly: -terrestrial (above sea level). -gentle dips are common -fossiliferous and may contain coal.
![Page 22: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/22.jpg)
![Page 23: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/23.jpg)
Conglomerate
Diabase (basalt) dike
![Page 24: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/24.jpg)
Unconsolidated Sediments
Crystalline metamorphic and igneous
rocks
Sedimentary Rocks
Appalachian Plateau
Blue Ridge Coastal Plain
Valley and Ridge Mesozoic Basins
Piedmont
![Page 25: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/25.jpg)
Blue Ridge Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite);
Metamorphic rocks (granulite, gneiss, schist, phyllite,greenstone, quartzite)
Clastic sedimentary rocks (sandstone, conglomerate, siltstone, shale) Age: Paleozoic to Proterozoic (550 - 1400 Ma)
-”basement” and “cover” rocks
-two major metamorphic events
-ductile faults in basement rocks
-brittle faults and folds in cover rocks
-separated from Valley and Ridge and Piedmont by faults in most places. -trace fossils only in youngest rocks.
![Page 26: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/26.jpg)
Blue Ridge basement rock, Amherst County, more than 1 billion years old
![Page 27: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/27.jpg)
Catoctin greenstone (metamorphosed basalt) I-64 near Rockfish Gap
![Page 28: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/28.jpg)
Antietam quartzite, youngest rock in Blue Ridge
Skolithos trace fossils
![Page 29: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/29.jpg)
Piedmont Intrusive and extrusive igneous rocks (granite, gabbro, basalt)
Metamorphic rocks (gneiss, schist schist, phyllite, quartzite, amphibolite) Age: Paleozoic to Proterozoic (300 – 750 Ma, rare 900 – 1400 Ma)
-several distinct terranes
-high to low grade metamorphism
-younger intrusive rocks
-ductile faults and younger brittle faults
-complex folds are common
-fossils are rare.
![Page 30: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/30.jpg)
Amphibolite
Gneiss
![Page 31: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/31.jpg)
Schist
Garnets in thin section of schist
![Page 32: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/32.jpg)
Columbia granite
Petersburg granite with pegmatite
![Page 33: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/33.jpg)
Mylonite (ductile fault rock)
![Page 34: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/34.jpg)
Unconsolidated Sediments
Crystalline metamorphic and igneous
rocks
Sedimentary Rocks
Appalachian Plateau
Blue Ridge Coastal Plain
Valley and Ridge Mesozoic Basins
Piedmont
![Page 35: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/35.jpg)
Coastal Plain Unconsolidated sediments
Sand-rich and clay-rich deposits Age: Cenozoic (0 – 65 Ma)
-marine and terrestrial deposits
-flat or gently dipping seaward
-developed during several periods of sea-level change. -some deposits are highly fossiliferous
![Page 36: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/36.jpg)
Sand-rich stream deposits formed when sea level was lower.
Antietam quartzite cobbles with
Skolithos in Coastal Plain sediments
![Page 37: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/37.jpg)
Clay-rich marine deposits
formed when sea level was higher
Chesapecten Jeffersonius (state fossil)
![Page 38: An Introduction to the Geology of Virginia€¦ · 12.03.2019 · Intrusive and extrusive igneous rocks (granite, charnockite, rhyolite); Metamorphic rocks (granulite, gneiss, schist,](https://reader036.fdocuments.net/reader036/viewer/2022070113/605d7d67538f673dc84365d1/html5/thumbnails/38.jpg)
Questions?