Oldest rock

The oldest rock and rocks on Earth, as an aggregate of minerals that have not been subsequently melted or disaggregated by erosion, are from the Archean Eon. Such rocks are only exposed on the surface in very few places.^[1]

There is some controversy about the oldest rocks based on the oldest dated mineral zircon. Some of the oldest surface rock can be found in the Canadian Shield, Australia, Africa and in other more specific places around the world. The ages of these felsic rocks are generally between 2.5 and 3.8 billion years. The approximate ages have a margin of error of millions of years. In 1999, the oldest known rock on earth has been dated to 4.031 ± 0.003 billion years, and is part of the Acasta Gneiss of the Slave craton in northwestern Canada.^[2] Since 2008, the oldest rock on earth has been discovered by McGill University in the Nuvvuagittuq Belt on the coast of Hudson Bay, in northern Quebec, and is dated from 3.8 to 4.28 billion years old.^[3]

Oldest rocks by category

Oldest terrestrial material

The oldest material of terrestrial origin that has been dated is a zircon mineral of 4,404 ± 8 Ma enclosed in a metamorphic gneiss in the Jack Hills of the Narryer Gneiss Terrane of Western Australia. The 4,404 ± 8 Ma zircon is a slight outlier, with the oldest consistently-dated zircon falling closer to 4.35 Ga.^[4] This zircon is part of a population of zircons within the gneiss of greater than 3,900 Ma; the gneiss is considered to be no older than 3,800 Ma, which is the age of the youngest zircon in the rock.

Earth's oldest rock formation

The oldest rock formation is, depending on the latest research, either part of the Isua Greenstone Belt, Narryer Gneiss Terrane or the Acasta Gneiss. The difficulty in assigning the title to one particular block of gneiss is that the gneisses are all extremely deformed, and the oldest rock may be represented by only one streak of minerals in a mylonite, representing a layer of sediment or an old dike. This may be difficult to find or map; hence the oldest dates yet resolved are as much generated by luck in sampling as by understanding the rocks themselves.

It is thus premature to claim that any of these rocks, or indeed that other formations of early Archaean gneisses, are the oldest formations or rocks on Earth; doubtless new analyses will continue to change our conceptions of the structure and nature of these ancient continental fragments.

Nevertheless, the oldest cratons on Earth include the Kaapvaal craton, the Western Gneiss Terrane of the Yilgarn craton (~2.9 - >3.2 Ga), the Pilbara Craton (~3.4 Ga), and portions of the Canadian Shield (~2.4 - >3.6 Ga). Parts of the poorly studied Dharwar craton in India are greater than 3.0 Ga. The oldest dated rocks of Baltic Shield are 3.5 Ga old ^[5].

Oldest rock on Earth

The Acasta Gneiss in the Canadian Shield in the Northwest Territories, Canada is composed of the Archaean igneous and gneissic cores of ancient mountain chains that have been exposed in a glacial peneplain. Analyses of zircons from a felsic orthogneiss with presumed granitic protolith returned an age of 4.031 ± 0.003 Ga^[2].

On September 25, 2008, researchers from McGill University, Carnegie Institution for Science and UQAM announced that a rock formation, the Nuvvuagittuq greenstone belt, exposed on the eastern shore of Hudson Bay in northern Quebec had a Sm-Nd age for extraction from the mantle of 4.28 billion years.^[6][7][8][9] However, it is argued that the actual age of formation of this rock, as opposed to the extraction of its magma from the mantle, is likely closer to 3.8 billion years, according to Simon Wilde of the Institute for Geoscience Research in Australia.^[10] But after O'Neil & al. continued their researches, they confirmed the date of the rocks by various other methods, which was to be the same as the chemical analysis.

Recent research

The zircons from the Western Australian Jack Hills returned an age of 4.404 billion years, interpreted to be the age of crystallization. These zircons also show another interesting feature; their oxygen isotopic composition has been interpreted to indicate that more than 4.4 billion years ago there was already water on the surface of the Earth. The importance and accuracy of these interpretations is currently the subject of scientific debate. It may be that the oxygen isotopes, and other compositional features (the rare earth elements), record more recent hydrothermal alteration of the zircons rather than the composition of the magma at the time of their original crystallization.. In a paper published in the journal Earth and Planetary Science Letters, a team of scientists suggest that rocky continents and liquid water existed at least 4.3 billion years ago and were subjected to heavy weathering by an acrid climate. Using a ion microprobe to analyze isotope ratios of the element lithium in zircons from the Jack Hills in Western Australia, and comparing these chemical fingerprints to lithium compositions in zircons from continental crust and primitive rocks similar to the Earth's mantle, they found evidence that the young planet already had the beginnings of continents, relatively cool temperatures and liquid water by the time the Australian zircons formed.^[11]

See also

• Archean
• Hadean
• Zircon
• History of Earth

References

• Zircons are Forever
• Bowring, S.A., and Williams, I.S., 1999. Priscoan (4.00-4.03 Ga) orthogneisses from northwestern Canada. Contributions to Mineralogy and Petrology, v. 134, 3-16.
• Stern, R.A., Bleeker, W., 1998. Age of the world's oldest rocks refined using Canada's SHRIMP. the Acasta gneiss complex, Northwest Territories, Canada. Geoscience Canada, v. 25, p. 27-31
• Yu A., Lee C-D and Halliday, A.N..Lutetium-Hafnium and Uranium-Lead Systematics of Early-Middle Archean Single Zircon Grains, Ninth Annual Goldschmidt Conference. 2

External links

• Very old Australian zircons with a story to tell
• On the Acasta Gneiss
• Yuichiro Ueno homepage
• Abstract and fullt ext of the results from O'Neil's research, published by Science

Oldest railroads in North America

Several railroads have been called the oldest in North America.

Early experimental railroads

• 1720: A railroad is reportedly used in the construction of the French fortress at Louisburg, Nova Scotia.^[1]
• 1764: Between 1762 and 1764 a gravity railroad (Montresor's Farmway) was built by British military engineers at the Niagara Portage in Lewiston, New York.
• 1795: A wooden railway on Beacon Hill in Boston carried excavations down the hill to clear the land for the State House.
• 1799: Boston developers begin to reduce the height of Mount Vernon, prior to building streets and homes. Silas Whitney constructs a gravity railroad to move excavated material down the hill to fill marshy areas to create new land from the Back Bay.^[2]
• 1809: In September an experimental railroad was built next to a Philadelphia tavern by a millwright named Somerville. The track, built for Thomas Leiper, has a grade of 1-1/2 inch to the yard (1 : 24 or about 4 %) over its total length of and proves satisfactory when tested with a loaded car.^[3]

• 1810: The Leiper Railroad, designed and built by merchant Thomas Leiper, connecting Crum Creek to Ridley Creek, Pennsylvania opened in 1810. It closed in 1829 and was replaced by the Leiper Canal, but a railroad once again replaced the canal in 1852. This became the Crum Creek Branch of the Baltimore and Philadelphia Railroad (part of the Baltimore and Ohio Railroad) in 1887. This was the first railroad meant to be permanent, and the first to evolve into a common carrier after an intervening closure. See the 1826 Granite Railway for comparison.
• 1811: George Magers designs and builds a wooden gravity railroad between a gunpowder mill and its powder storage bunker at Falling's Creek, Virginia.^[4]
• 1815: New Jersey grants a charter on February 6, 1815 for a company to "erect a rail-road from the river Delaware near Trenton, to the river Raritan, at or near New Brunswick", as proposed by John Stevens (1749-1838). This was the first railroad chartered in the United States, but the New Jersey Railroad Company never built the railway due to an inability to attract financial investors.
• 1816: A railroad is reportedly used at Kiskiminetas Creek, Pennsylvania.^[5]
• 1818: An iron-smelting funace at Bear Creek, Armstrong County, Pennsylvania reportedly has a wooden railroad in operation.^[5]

The Granite, Coal and Cotton Railroads

Mohwak and Hudson Historical Marker

• 1826: The Granite Railway in Massachusetts was incorporated March 4, 1826 by Thomas Handasyd Perkins and Gridley Bryant. Construction began on April 1, 1826, and operations began on October 7, 1826.^[6] It later became a branch of the Old Colony and Newport Railroad, which was later absorbed into the New York, New Haven and Hartford Railroad. This is often called the first commercial railroad in the U.S., as it was the first to evolve into a common carrier without an intervening closure. See the 1810 Leiper Railroad for comparison.
• 1826: The Mohawk and Hudson Railroad, became the first railroad chartered in New York State.^[7]
• 1827: The Mauch Chunk Railroad, a gravity railroad, is built between Summit Hill and Mauch Chunk, Pennsylvania, (now Jim Thorpe, PA).^[8] It was built to haul anthracite coal from the mines to the Lehigh River and was the first railroad of this type.
• 1829: The Delaware and Hudson Canal Company's gravity railroad in northeast Pennsylvania opened, with the Stourbridge Lion, the first locomotive to run on rails in the United States, first operating on August 8.^[9] It was also a coal railroad. The canal company, chartered in 1823, called itself "America's oldest continually operated transportation company".
• 1829: The South Carolina Canal and Rail Road Company was chartered December 19, 1827 and was also known as the Charleston & Hamburg Road. An experimental track was installed in February, 1829 to haul bales of cotton in downtown Charleston, South Carolina. On April 1, 1830 a double tracked long railroad was in full operation. By 1833, this railroad had been completed to Hamburg, South Carolina for a total length of . At that time, it was the longest railroad in the world. This was the first railroad to use steam locomotives regularly. It later became part of the Southern Railway, now part of Norfolk Southern.^[10]
• 1829: The Mill Creek & Mine Hill Navigation & Railroad Company was chartered on February 7, 1828. The main line from From Palo Alto, Pennsylvania to Wolf Creek was completed in 1829 with branches added in 1829 and 1830 for a total of .^[11] It was another coal hauling railroad.
• 1830: The Schuylkill Valley Railroad & Navigation Company was chartered on April 14,1828. It ran from Port Carbon, Pennsylvania to Tuscarora and was completed in 1830.^[12] It was built to carry coal from mines to Port Carbon.
• 1830: The Union Canal Company Railroad was a railroad constructed by the Union Canal (Pennsylvania) Company and was chartered on March 3, 1826. The company was in the canal business, but due to the topography, they could not extend their canal to the coal fields north of Pine Grove, Pennsylvania. Their solution was to build this short coal hauling railroad which was completed in 1830.^[9]
• 1830: The Tuscumbia Railway was chartered on January 16, 1830 and proceeded to build a railroad from downtown Tuscumbia, Alabama to the docks on the Tennessee River west of Sheffield. This was the first railroad chartered/constructed west of the Appalachian Mountains. In 1832, this railroad was renamed the Tuscumbia, Courtland and Decatur Railroad, and was extended to connect the two Alabama cities of Tuscumbia and Decatur.^[13]
• 1831: The Mount Carbon Railroad was completed in 1831 running from Mount Carbon, Pennsylvania through Pottsville where it split into two branches, one going to what is now Seltzer and the other to the current Wadesville. This was a coal hauling railroad, in length.^[14]
• 1831: The Mine Hill and Schuylkill Haven Railroad completed the first part of its railroad from Schuylkill Haven, Pennsylvania to Minersville with a branch line up the West Branch of the Schuylkill River, a distance of .^[15]
• 1831: The Room Run Railroad was completed running a distance from Mauch Chunk, Pennsylvania to Nesquehoning.^[16]
• 1831: The Chesterfield Railroad (sometimes called the Manchester Railroad) began operations by September 1831 in Chesterfield County, Virginia.^[16]
• 1839: Albion Railway serving coal mines around Stellarton, Nova Scotia, first railway in Canada is use iron rails and run year-round, home of Samson, the oldest surving locomotive in Canada.

Common carriers

Selected railroads chartered since 1832:

• 1835: The New Orleans and Carrollton Railroad begins operation after 4 years of work; rail route still in operation as the St. Charles Streetcar Line in New Orleans.
• 1836: The Lake Wimico and St. Joseph Canal and Railroad Company was the first steam railroad in Florida, opening on September 5.
• 1836: The Champlain and St. Lawrence Railroad opens in Quebec, Canada.

Tunnels and Bridges

• 1829: Carrollton Viaduct built of stone for Baltimore & Ohio Railroad, over Gwynns Falls River in Baltimore MD
• 1833 (June): The Staple Bend Tunnel, the first railroad tunnel in the U.S., completed in June 1833 as part of the Allegheny Portage Railroad which opened in March 1834. Trains stopped running through the Staple Bend Tunnel in 1857, and it is now part of the Allegheny Portage Railroad National Historic Site.^[17]
• 1833 (December): Wadesville Tunnel, built by Danville and Pottsville Railroad at Wadesville, Pennsylvania.^[18]
• 1835: Thomas Viaduct built of stone for Baltimore & Ohio Railroad, over Patapsco River in Relay, MD
• 1835: Canton Viaduct built of stone for Boston & Providence Railroad, over Canton River in Canton, MA
• 1837: The Yorkville Tunnel opened on October 26, for the New York and Harlem Railroad. It was absorbed in the 1870s by the longer and wider Park Avenue Tunnel, and is used by all Metro-North Railroad commuter trains. The old tunnel carries the two center tracks, and two new tunnels carry outer tracks.
• 1837: The Taft Tunnel opened in 1837 for Norwich and Worcester Railroad in Lisbon, Connecticut, north of Norwich, Connecticut. This is the oldest tunnel still in use in its original form in the U.S.
• 1837: The Howard Tunnel in York County, Pennsylvania. Considered the second oldest tunnel still in use in its original form in the U.S.
• 1842: The Potomac Creek Bridge long was built across the Potomac Creek in Stafford County, Virginia.
• 1848: Starrucca Viaduct built of stone for Erie Railroad, over Starrucca Creek in Lanesboro, PA
• 1850: The Henryton Tunnel on the Baltimore and Ohio Railroad.

West of the Mississippi River

• 1841: The Red River Railroad between Alexandria and Cheneyville in Louisiana was operational by 1841.^[19]
• 1852: The first section of the Pacific Railroad, later part of the Missouri Pacific Railroad, opened near St. Louis, Missouri.

References

External links

• American Railroads; Their Growth and Development by Association of American Railroads (Washington DC, 1956)
• Library of Congress - History of Railroads and Maps
• Railroad History Database
• http://www.nrhs.com/almanac/index.html National Railway Historical Society (NRHS): Historical Almanac of American Railroads - US, Canada, Mexico
• William D. Middleton, Where is America's oldest railroad tunnel?, Trains May 2002

Specific railroads

• First Permanent Railroad In The U. S. And Its Connection To The University Of Pennsylvania (Leiper Railroad)
• The First Railroad in America 1826-1926: A History of the Origin and Development of the Granite Railway at Quincy, Massachusetts