Читать книгу The Circle of Knowledge: A Classified, Simplified, Visualized Book of Answers - Various - Страница 67

Table of Contents

Giving the geological ages, rock systems, strata and the development of life, with their relative positions and order of succession, according to the latest scientific knowledge. Many attempts have been made to compute from geological, physical, and other data the length of the period during which the earth has been in a solid state.

Geologists, however, are disinclined to accept any period much less than 100,000,000 years as sufficient for the elaboration of the present structure of the earth. It is indisputable that many millions of years, probably thirty or forty, must have elapsed while the great sedimentary rocks were being deposited. With respect to the larger features of the earth’s surface, it is likely that two different kinds of movement are responsible. Where the contraction of the earth has caused a lessening of the support below the surface, there has been a subsidence of great areas. In the second place, where the rigid crust has been able to contract into a smaller space, great mountain ridges and folds have been formed. The subsidences which caused the ocean took place at different ages. The Atlantic Ocean probably dates from middle Cenozoic times; the Indian Ocean may be older; the Pacific suffered great modifications in comparatively recent times.

Life Ages of the Earth	Rock Systems	Series of Rock Strata	Characteristic Rocks	Forms of Life	Chief Economic Products
Cenozoic (se´nō-zō´ik), or “Recent life.” Estimated Age of Period, 3,000,000 years.	Quaternary (kwa-ter´na-ri) or “fourth.” Once supposed to be the fourth sedimentary system. Age of man.	Recent, or Human.	Alluvium, sand, gravel, mud, clay, marl, loess.	Man predominant.	Clay, peat, bog iron ore, marl, gold placers.
Pleistocene (plīs´tŏ-sēn), or “most recent.” Glacial Period.	Drift, boulder clay, gravel, loess, silt, glacial deposits and other formations formed during glacial period.	Mammoth, mastodon, bear, bison, reindeer, musk-ox. Possibly man was living but that is uncertain.	Clay, gravel, gold placers.
Pliocene (plī´ō-sēn), or “more recent.”	In East and West, land deposits predominate. Marine sands, clays, marls on Atlantic and Pacific coasts. Igneous rocks in West.	Plants and animals much as today, aside from human and domestic species.	Gold (in part placers), coal, oil, gas.
Tertiary (ter´-shi-a-ri), or “third”. Once supposed to be the third sedimentary system, or Age of mammals.	Miocene (mī´ō-sēn), or “less recent.”	On Atlantic coast: sand, clay, shell marl, diatomaceous earth. In West: sandstone, shale, and diatomaceous material. Extensive volcanic formations in Rocky Mountains and Great Basin region.	Land animals include elephants, camels, deer, oxen, horses, true apes, etc. Marine animals much like those today. Among plants, grasses become important; deciduous trees increase.	Silver, gold, coal, oil, gas, phosphate rock, diatomaceous earth.
Oligocene (ŏl´ĕ-gō-sēn), or “a little more recent.”	Limestone in Caribbean region, land deposits in West. Marine and fresh water beds on west coast. Many coal beds in Puget Sound.	Ancient dogs, cats, rabbits, squirrels, camels, and horses were represented.	Copper, silver.
Eocene (ē´-ō-sēn), or “dawn of recent.”	In Eastern States: clays, sands, greensand marls. In West: conglomerate, sandstone, shale, diatomaceous shale and igneous formations are developed. Many coal beds in Puget Sound. Fresh water beds in western interior.	Mammals flourished, including rodentia, carnivera, edentates, lemuroids, birds, reptiles, etc. Flora included figs, palms, bananas; willows, chestnuts, oaks, etc.	Gold, zinc, lead, coal, oil, gas.
Mesozoic (mĕs-ō-zō´-ic), or “Middle life,” Estimated Age of Period, 9,000,000 years.	Cretaceous (krē-ta´-she-us) or “bearing chalk.”	-		Upper.	In East: sand, clay, and greensand marl. In West: sandstone, shale, limestone, chalk, extensive coal beds, various igneous rocks.	Reptiles predominate: turtles, lizards, crocodiles, flying reptiles, etc. Many waterbirds. Angiosperms predominate: larch, beech, walnut, tulip trees, etc.	Coal, oil, gas, copper, gold, china clay, fire clay, cement building stone.
Lower.	Clay, sand, gravel on Atlantic coast and Gulf. Sedimentary and igneous rocks on west coast. Some non-marine beds in Texas.	Reptiles abound. Flora includes cycadeous, conifers, horsetails; angiosperms appear.
Jurassic (jȯȯ-ras´sik), or like the mass of the Jura Mountains. Age of Reptiles.	-		Upper.	Probably not represented in East. Sandstones, limestones and shales in West. Some “red beds” in western interior.	Ammonites, belemites continue in great variety. Reptiles numerous and varied types. Flying reptiles and reptile-like birds appear.	Oil, gold.
Middle.
Lower.
Triassic (trĭ-ăs´ĭk), or in a triple series.	-		Upper.	In East sediments formed in shallow troughs between recently formed mountains. Considerable bodies of igneous rock, traps, and other flows and dikes. “Red beds” in West with salt and gypsum. Some igneous rocks on west coast.	Reptiles of enormous size dominate the land and sea. Mammals appear. Ammonites and belemites dominate invertebrate life.	Salt, gypsum, a little coal in Virginia, copper, building stone.
Middle.
Lower.
Paleozoic (pāl-æ-ô-zō´ic), or “Old life.” Estimated Age of Period, 24,000,000 years.	Carboniferous (kăr-bŏn-if´-er-us), or coal-bearing. Age of Amphibians.	Permian (per´-mē-ăn), like those at Perm, Russia.	In East fresh water sediments including coal; in West “red beds” probably of continental origin. Some marine sediments; salt and gypsum in red beds in Kansas.	Reptiles become prominent in number and variety; inhabit fresh water, salt water and land.	Salt and gypsum; some coal in Eastern States.
Pennsylvanian, like those of Pennsylvania.	In Eastern States grits, sandstones, shales, limestone and coal. In Western States much limestone; no coal. Igneous rocks on west coast.	Plants abound; Marked development of land animals, including insects, spiders and scorpions. Lizards become important. Amphibians reach climax.	Coal, oil, gas, iron ore, fire clay, phosphate rock.
Mississippian, or Lower Carboniferous.	Limestones predominate with sandstones near base and shales near top of series. Igneous rocks in California.	Crinoids greatly developed. Amphibians appear. Plant life expands.	Oil, gas, lead, zinc, building stone, cement rock.
Devonian (de-vō´ni-an) like those of Devonshire, England. Age of Fishes.	-		Upper.	Sedimentary rocks, limestones, sandstones, shales; igneous rocks in Maine, Nova Scotia, and New Brunswick.	Rapid changes in animal kingdom; shifting habitat; extensive development of fishes; sharks flourish. Plants are mainly small leaf and reed types.	Gas, oil, iron ore, phosphate rock.
Middle.
Lower.
Silurian (si-lū´ri-an), in the land of the Silures, England. Age of Invertebrates.	-		Ontarian (on-tā´rē-ăn), place name.	Sedimentary rocks predominate; conglomerates, sandstones, shales, limestones, salt, gypsum. Igneous rocks in Nova Scotia, New Brunswick, and Maine.	Vertebrates appear; low forms of fishes. First reef building corals. Crinoids and brachiopods, important Cephalopods continue to dominate.	Iron ore, gas, salt, gypsum, cement rock.
Champlainian (shăm-plān´ē-ăn), place name.
Ordovician (ŏr-dŏ-vīsh´ăn), a place name in Wales.	-		Cincinnatian (sĭn-sĭn-năt´-ē-ăn), place name.	Chiefly limestone with subordinate sandstone and shale. Rocks greatly folded in New York, in Taconic Mountain region.	Much as in the Cambrian. Remains are more abundant. Species more numerous; insects were present. Vertebrates appear. Low forms of fishes. Trilobites reach climax.	Oil, gas, lead, zinc, phosphate rock, manganese, marble.
Mohawkian (mō-hŏk´ē-ăn), place name.
Lower.
Cambrian (kam´-bri-an), from Cambria, the old name for Wales.	-		Saratogan (săr-ă-tō´găn), place name.	Mainly sandstones with some shales, and in Western States considerable limestone. At some places rocks are changed by pressure, especially in the Appalachian Mountains. Upper Cambrian covered larger area than lower Cambrian.	All great divisions of animal kingdom except vertebrates are represented; trilobites, brachiopods, sponges, graptolites, etc. Little evidence of vegetation, but it must have abounded as food for animals.	Lead, zinc, barite, copper.
Acadian (ä-kād´ē-ăn), place name.
Georgian (jōr´gē-ăn), place name.
Proterozoic (prō-ter-ō-zō´ik) or “Former life.” Estimated Age of Period, 18,000,000 years.	Algonkian (ăl-gŏn´kē-ăn), from district of Algonquin Indians, north of St. Lawrence.	-		Keweenawan, (kē´wē-năh-wān), pertaining to Keweenaw Peninsula, Michigan.	A great series of sandstones, limestones and shales, in middle portion of which are many enormous flows of lava.	Fossils rare or wanting.	Copper, silver.
Huronian (hu-rō´nē-ăn), rocks on borders of Lake Huron.	Three great series of sedimentary rocks, sandstone, shale and limestone, and iron formation. Contains also many great igneous bodies, acidic and basic. Lower members much metamorphosed by pressure.	Rocks contain clear evidence of low forms of life.	Principal iron ores of Lake Superior region; also copper, nickel, silver, cobalt, gold. Building stone and ornamental stone.
Archaeozoic (ar´kē-o-zō´ic), “Without life.” Estimated Age of Period, 18,000,000 years.	Archean (är-kē´-ăn), “oldest.”	-		Laurentian (law-ren´shi-an), pertaining to rocks along the St. Lawrence River.	Granitic rocks and gneisses that are believed to be granitic rocks metamorphosed by pressure. Formerly supposed to be older than Keewatin and regarded as the “original crust of the earth.”	Since the rocks are of igneous origin, they contain no organic remains.	Iron ores, precious metals, gems, apatite, rare earths, graphite, asbestos.
Keewatin (kē-wā´tĭn), rocks in a district of Manitoba, Canada.	A great schist series made up of lava flows, tuffs, and volcanic ashes. With these are subordinate sedimentary rocks; sandstone, shale, limestone, and iron ore formations nearly everywhere greatly metamorphosed by pressure. Includes the oldest rocks known.	No fossils found, but carbonaceous schists and limestones are believed to indicate the presence of life.	Emery, building and ornamental stones.

Life Ages of the Earth	Rock Systems	Series of Rock Strata	Characteristic Rocks	Forms of Life	Chief Economic Products
Cenozoic (se´nō-zō´ik), or “Recent life.” Estimated Age of Period, 3,000,000 years.	Quaternary (kwa-ter´na-ri) or “fourth.” Once supposed to be the fourth sedimentary system. Age of man.	Recent, or Human.	Alluvium, sand, gravel, mud, clay, marl, loess.	Man predominant.	Clay, peat, bog iron ore, marl, gold placers.
		Pleistocene (plīs´tŏ-sēn), or “most recent.” Glacial Period.	Drift, boulder clay, gravel, loess, silt, glacial deposits and other formations formed during glacial period.	Mammoth, mastodon, bear, bison, reindeer, musk-ox. Possibly man was living but that is uncertain.	Clay, gravel, gold placers.
		Pliocene (plī´ō-sēn), or “more recent.”	In East and West, land deposits predominate. Marine sands, clays, marls on Atlantic and Pacific coasts. Igneous rocks in West.	Plants and animals much as today, aside from human and domestic species.	Gold (in part placers), coal, oil, gas.
	Tertiary (ter´-shi-a-ri), or “third”. Once supposed to be the third sedimentary system, or Age of mammals.	Miocene (mī´ō-sēn), or “less recent.”	On Atlantic coast: sand, clay, shell marl, diatomaceous earth. In West: sandstone, shale, and diatomaceous material. Extensive volcanic formations in Rocky Mountains and Great Basin region.	Land animals include elephants, camels, deer, oxen, horses, true apes, etc. Marine animals much like those today. Among plants, grasses become important; deciduous trees increase.	Silver, gold, coal, oil, gas, phosphate rock, diatomaceous earth.
		Oligocene (ōl´ĕ-gō-sēn), or “a little more recent.”	Limestone in Caribbean region, land deposits in West. Marine and fresh water beds on west coast. Many coal beds in Puget Sound.	Ancient dogs, cat, rabbits, squirrels, camels, and horses were represented.	Copper, silver.
		Eocene (ē´-ō-sēn), or “dawn of recent.”	In Eastern States: clays, sands, greensand marls. In West: conglomerate, sandstone, shale, diatomaceous shale and igneous formations are developed. Many coal beds in Puget Sound. Fresh water beds in western interior.	Mammals flourished, including rodentia, carnivera, edentates, lemuroids, birds, reptiles, etc. Flora included figs, palms, bananas; willows, chestnuts, oaks, etc.	Gold, zinc, lead, coal, oil, gas.
Mesozoic (mĕs-ō-zō´-ic), or “Middle Life.” Estimated Age of Period, 5,000,000 years.	Cretaceous (krē-ta´-she-us) or “bearing chalk.”	-		Upper.	In East: sand, clay, and greensand marl. In West: sandstone, shale, limestone, chalk, extensive coal beds, various igneous rocks.	Reptiles predominate: turtles, lizards, crocodiles, flying reptiles, etc. Many waterbirds. Angiosperms predominate: larch, beech, walnut, tulip trees, etc.	Coal, oil, gas, copper, gold, china clay, fire clay, cement building stone.
Lower.	Clay, sand, gravel on Atlantic coast and Gulf. Sedimentary and igneous rocks on west coast. Some non-marine beds in Texas.	Reptiles abound. Flora includes cycadeous, conifers, horsetails; angiosperms appear.
	Jurassic (jȯȯ-ras´sik), or like the mass of the Jura Mountains. Age of Reptiles.	-		Upper.	Probably not represented in East. Sandstones, limestones and shales in West. Some “red beds” in western interior.	Ammonites, belemites continue in great variety. Reptiles numerous and varied types. Flying reptiles and reptile-like birds appear.	Oil, gold.
Middle.
Lower.
	Triassic (trĭ-ăs´ĭk), or in a triple series.	-		Upper.	In East sediments formed in shallow troughs between recently formed mountains. Considerable bodies of igneous rock, traps, and other flows and dikes. “Red beds” in West with salt and gypsum. Some igneous rocks on west coast.	Reptiles of enormous size dominate the land and sea. Mammals appear. Ammonites and belemites dominate invertebrate life.	Salt, gypsum, a little coal in Virginia, copper, building stone.
Middle.
Lower.
Paleozoic (pāl-æ-ô-zō´ic), or “Old Life.” Estimated Age of Period, 24,000,000 years.	Carboniferous (kăr-bŏn-if´-er-us), or coal-bearing. Age of Amphibians.	Permian (per´-mē-ăn), like those at Perm, Russia.	In East fresh water sediments including coal; in West “red beds” probably of continental origin. Some marine sediments; salt and gypsum in red beds in Kansas.	Reptiles become prominent in number and variety; inhabit fresh water, salt water and land.	Salt and gypsum; some coal in Eastern States.
Pennsylvanian, like those of Pennsylvania.	In Eastern States grits, sandstones, shales, limestone and coal. In Western States much limestone; no coal. Igneous rocks on west coast.	Plants abound. Marked development of land animals, including insects, spiders and scorpions. Lizards become important. Amphibians reach climax.	Coal, oil, gas, iron ore, fire clay, phosphate rock.
Mississippian, or Lower Carboniferous.	Limestones predominate with sandstones near base and shales near top of series. Igneous rocks in California.	Crinoids greatly developed. Amphibians appear. Plant life expands.	Oil, gas, lead, zinc, building stone, cement rock.
	Devonian (de-vō´ni-an) like those of Devonshire, England. Age of Fishes.	-		Upper.	Sedimentary rocks, limestones, sandstones, shales; igneous rocks in Maine, Nova Scotia, and New Brunswick.	Rapid changes in animal kingdom; shifting habitat; extensive development of fishes; sharks flourish. Plants are mainly small leaf and reed types.	Gas, oil, iron ore, phosphate rock.
Middle.
Lower.
	Silurian (si-lū´ri-an), in the land of the Silures, England. Age of Invertebrates.	-		Ontarian (on-tā´rē-ăn), place name.	Sedimentary rocks predominate; conglomerates, sandstones, shales, limestones, salt, gypsum. Igneous rocks in Nova Scotia, New Brunswick, and Maine.	Vertebrates appear; low forms of fishes. First reef building corals. Crinoids and brachiopods, important Cephalopods continue to dominate.	Iron ore, gas, salt, gypsum, cement rock.
Champlainian (shăm-plān´ē-ăn), place name.
	Ordovician (ŏr-dŏ-vīsh´ăn), a place name in Wales.	-		Cincinnatian (sĭn-sĭn-năt´-ē-ăn), place name.	Chiefly limestone with subordinate sandstone and shale. Rocks greatly folded in New York, in Taconic Mountain region.	Much as in the Cambrian. Remains are more abundant. Species more numerous; insects were present. Vertebrates appear. Low forms of fishes. Trilobites reach climax.	Oil, gas, lead, zinc, phosphate rock, manganese, marble.
Mohawkian (mō-hŏk´ē-ăn), place name.
Lower.
	Cambrian (kam´-bri-an), from Cambria, the old name for Wales.	-		Saratogan (săr-ă-tō´găn), place name.	Mainly sandstones with some shales, and in Western States considerable limestone. At some places rocks are changed by pressure, especially in the Appalachian Mountains. Upper Cambrian covered larger area than lower Cambrian.	All great divisions of animal kingdom except vertebrates are represented; trilobites, brachiopods, sponges, graptolites, etc. Little evidence of vegetation, but it must have abounded as food for animals.	Lead, zinc, barite, copper.
Acadian (ä-kād´ē-ăn), place name.
Georgian (jōr´gē-ăn), place name.
Proterozoic (prō-ter-ō-zō´ik) or “Former Life.” Estimated Age of Period, 18,000,000 years.	Algonkian (ăl-gŏn´kē-ăn), from district of Algonquin Indians, north of St. Lawrence.	-		Keweenawan, (kē´wē-năh-wān), pertaining to Keweenaw Peninsula, Michigan	A great series of sandstones, limestones and shales, in middle portion of which are many enormous flows of lava.	Fossils rare or wanting.	Copper, silver.
Huronian (hu-rō´nē-ăn), rocks on borders of Lake Huron.	Three great series of sedimentary rocks, sandstone, shale and limestone, and iron formation. Contains also many great igneous bodies, acidic and basic. Lower members much metamorphosed by pressure.	Rocks contain clear evidence of low forms of life.	Principal iron ores of Lake Superior region; also copper, nickel, silver, cobalt, gold. Building stone and ornamental stone.
Archaeozoic (ar´kē-o-zō´ic), “Without Life.” Estimated Age of Period, 18,000,000 years.	Archean (är-kē´-ăn), “oldest.”	-		Laurentian (law-ren´shi-an), pertaining to rocks along the St. Lawrence River.	Granitic rocks and gneisses that are believed to be granitic rocks metamorphosed by pressure. Formerly supposed to be older than Keewatin and regarded as the “original crust of the earth.”	Since the rocks are of igneous origin, they contain no organic remains.	Iron ores, precious metals, gems, apatite, rare earths, graphite, asbestos.
Keewatin (kē-wā´tĭn), rocks in a district of Manitoba, Canada.	A great schist series made up of lava flows, tuffs, and volcanic ashes. With these are subordinate sedimentary rocks; sandstone, shale, limestone, and iron ore formations nearly everywhere greatly metamorphosed by pressure. Includes the oldest rocks known.	No fossils found, but carbonaceous schists and limestones are believed to indicate the presence of life.	Emery, building and ornamental stones.