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54-815: The extent of this intrusion was originally mapped in 1892 as the "Woodstock granite". It was given its current name in 1964 by C. A. Hopson. Hopson grouped the Woodstock Quartz Monzonite with the Ellicott City Granodiorite and the Guilford Quartz Monzonite as "Late-kinematic intrusive masses." Woodstock granite has been used in the Capitol Building , the Library of Congress , and in buildings in Baltimore. The Woodstock Quartz Monzonite

108-411: A food web based on as-yet-undiscovered detritivores and grazers on micro-organisms. Millipedes from Cowie Formation such as Cowiedesmus and Pneumodesmus were considered as the oldest millipede from the middle Silurian at 428–430 million years ago, although the age of this formation is later reinterpreted to be from the early Devonian instead by some researchers. Regardless, Pneumodesmus

162-514: A high degree of development in relation to the age of its fossil remains. Fossils of this plant have been recorded in Australia, Canada, and China. Eohostimella heathana is an early, probably terrestrial, "plant" known from compression fossils of Early Silurian (Llandovery) age. The chemistry of its fossils is similar to that of fossilised vascular plants, rather than algae. Fossils that are considered as terrestrial animals are also known from

216-485: A large ocean occupied most of the northern half of the globe. The high sea levels of the Silurian and the relatively flat land (with few significant mountain belts) resulted in a number of island chains, and thus a rich diversity of environmental settings. During the Silurian, Gondwana continued a slow southward drift to high southern latitudes, but there is evidence that the Silurian icecaps were less extensive than those of

270-652: A mile northwest and southeast. Although so small, it is one of the most important economic areas within the state. This mass of granite, which is evidently intruded into the gneisses, is entirely enveloped by them and sends no dikes or apophyses into the surrounding rock. That the gneiss is really older than the granite is shown by the great number of inclusions found within the latter. These are chiefly of gneiss, and they occur often in huge irregular blocks six to eight or even ten feet in size, showing narrow rims due to contact metamorphism. They are beautifully puckered and wrinkled and being much richer in ferro-magnesian silicates than

324-423: A minor mass extinction and associated with rapid sea-level change. Each one leaves a similar signature in the geological record, both geochemically and biologically; pelagic (free-swimming) organisms were particularly hard hit, as were brachiopods , corals , and trilobites , and extinctions rarely occur in a rapid series of fast bursts. The climate fluctuations are best explained by a sequence of glaciations, but

378-587: A radiometric date of the Woodstock Quartz Monzonite of 420 +/-50 Ma ( Silurian ). In 1998, A. A. Drake reported an age of 444 Ma ( Ordovician ), and suggested it may be comagmatic with the Guilford Quartz Monzonite . Woodstock granite can be found in the United States Capitol , Thomas Viaduct , "the Library of Congress , the inner walls of the Washington Monument , the Old Patent Office , and

432-590: A railroad two miles long to connect with the Baltimore and Ohio at Putney and Riddle's bridge, about one mile east of Woodstock. Their first contract of importance was furnishing stone for the Baltimore Custom House . They, however, continued the business only a few years. Extravagance and mismanagement caused the failure, and they were succeeded by Edward Green and Joshua B. Sumwalt, under the firm-name of Green & Sumwalt. The senior partner dying about 1849, he

486-514: A second supercontinent known as Euramerica . When the proto-Europe collided with North America, the collision folded coastal sediments that had been accumulating since the Cambrian off the east coast of North America and the west coast of Europe. This event is the Caledonian orogeny , a spate of mountain building that stretched from New York State through conjoined Europe and Greenland to Norway. At

540-622: A short while, when he associated with him Wm. H. Johnson, of Baltimore, and they soon after formed with George Mann, Hugh Hanna, Messrs. Grey & Sons, of Philadelphia, and Mr. Hamilton of Baltimore, a joint stock company, calling it the Guilford and Waltersville Granite Co. This company is now (in 1898) conducting the business. "The two largest quarries were Waltersville and Fox Rock. These and smaller quarries counted hundreds of stonecutters among their employees." The quarries near Granite were "most active after 1875." In 1966, G. W. Wetherill reported

594-408: Is "a fine grained mass, with a decided foliation or gneissic structure," while the rock on the western, or Howard County side, is "more uniform and granitic." The text also refers to the figure of the polished slab on the left: "Here it also has a porphyritic structure in consequence of the development of large flesh-colored crystals of feldspar which are disseminated somewhat irregularly through

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648-663: Is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago ( Mya ), to the beginning of the Devonian Period, 419.2 Mya. The Silurian is the third and shortest period of the Paleozoic Era, and the third of twelve periods of the Phanerozoic Eon. As with other geologic periods , the rock beds that define the period's start and end are well identified, but

702-546: Is made of these quarries. It is not certain whether the quarry on the Baltimore county side or the quarries of the Howard county side furnished the first material for Baltimore, but it is clearly evident from the character of the rock furnished for the Catholic Cathedral , that the gneiss was the more important rock at that time. Local tradition assigns the source of the stone sometimes to the Baltimore county side and sometimes to

756-600: Is on River Road, 0.3 miles east of the Patapsco River Bridge, Ellicott City, and H18-1A is on U.S. Route 29 , 200 yards south of U.S. Route 40 . The 1898 account of Edward B. Mathews of the Maryland Geological Survey of the quarries at Ellicott City begins with a statement that there were two quarries; one on either side of the Patapsco River . The rock on the eastern, or Baltimore County, side

810-549: Is still an important fossil as the oldest definitive evidence of spiracles to breath in the air. The first bony fish, the Osteichthyes , appeared, represented by the Acanthodians covered with bony scales. Fish reached considerable diversity and developed movable jaws , adapted from the supports of the front two or three gill arches. A diverse fauna of eurypterids (sea scorpions)—some of them several meters in length—prowled

864-632: The Baltimore Custom House ." Ellicott City Granodiorite The Ellicott City Granodiorite is a Silurian or Ordovician granitic pluton in Howard and Baltimore Counties, Maryland. It is described as a biotite granodiorite along the margin of the intrusion which grades into a quartz monzonite in its core. It intrudes through the Wissahickon Formation and the Baltimore Gabbro Complex . In 1964, C. A. Hopson grouped

918-535: The Smithsonian building , twice passed by these quarries and yet makes no mention of them. At the time of the Tenth Census the agent remarks that he "knows of no other place in the country where there are so many stone buildings in an area of the same size." Mathews described recent (c. 1872-1898) operations at the quarries: Of the quarries in operation at the present day those of Werner Bros, were opened as early as

972-574: The South Pole until they almost disappeared in the middle of Silurian. Layers of broken shells (called coquina ) provide strong evidence of a climate dominated by violent storms generated then as now by warm sea surfaces. The climate and carbon cycle appear to be rather unsettled during the Silurian, which had a higher frequency of isotopic excursions (indicative of climate fluctuations) than any other period. The Ireviken event , Mulde event , and Lau event each represent isotopic excursions following

1026-489: The "Waltersville" and "Fox Rock." The former is the principal one, and was at first called the "Branch." This rock developed into a fine ledge, surpassing all the granite around in quantity, quality and easy access, so that all the boulders in which Sweatt, Putney and Riddle were interested were at once abandoned. After working it for a year or two Putney and Riddle obtained a lease of this quarry for twenty years in August, 1835, from

1080-715: The Ellicott City Granodiorite with the Guilford Quartz Monzonite and the Woodstock Quartz Monzonite as "Late-kinematic intrusive masses." In 1980, Crowley and Reinhardt of the Maryland Geological Survey remapped the Ellicott City Quadrangle and referred to this unit as the Ellicott City Granite, rather than granodiorite. Hopson reported the chemical composition (by %) of the Ellicott City Granodiorite from two locations. H7-A

1134-451: The Howard county side and the published information is equally conflicting and indefinite. When the Cathedral was constructed during the years 1806 to 1812 and subsequently from 1815 to 1821, the material was hauled from Ellicott City to Baltimore along the old Frederick road in huge wagons drawn by nine yoke of oxen . After furnishing the rock for this building, which must have been one of

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1188-665: The Llandovery and Wenlock. Trilobites started to recover in the Rhuddanian, and they continued to enjoy success in the Silurian as they had in the Ordovician despite their reduction in clade diversity as a result of LOME. The Early Silurian was a chaotic time of turnover for crinoids as they rediversified after LOME. Members of Flexibilia, which were minimally impacted by LOME, took on an increasing ecological prominence in Silurian seas. Monobathrid camerates, like flexibles, diversified in

1242-482: The Llandovery, whereas cyathocrinids and dendrocrinids diversified later in the Silurian. Scyphocrinoid loboliths suddenly appeared in the terminal Silurian, shortly before the Silurian-Devonian boundary, and disappeared as abruptly as they appeared very shortly after their first appearance. Endobiotic symbionts were common in the corals and stromatoporoids. Rugose corals especially were colonised and encrusted by

1296-574: The Order in which the Older Sedimentary Strata Succeed each other in England and Wales, which was the germ of the modern geological time scale . As it was first identified, the "Silurian" series when traced farther afield quickly came to overlap Sedgwick's "Cambrian" sequence, however, provoking furious disagreements that ended the friendship. The English geologist Charles Lapworth resolved

1350-470: The Silures show little correlation ( cf . Geologic map of Wales , Map of pre-Roman tribes of Wales ), Murchison conjectured that their territory included Caer Caradoc and Wenlock Edge exposures - and that if it did not there were plenty of Silurian rocks elsewhere 'to sanction the name proposed'. In 1835 the two men presented a joint paper, under the title On the Silurian and Cambrian Systems, Exhibiting

1404-481: The Silurian was the diversification of jawed fish , which include placoderms , acanthodians (which gave rise to cartilaginous fish ) and osteichthyan ( bony fish , further divided into lobe-finned and ray-finned fishes )， although this corresponded to sharp decline of jawless fish such as conodonts and ostracoderms . The Silurian system was first identified by the Scottish geologist Roderick Murchison , who

1458-518: The Silurian. The definitive oldest record of millipede ever known is Kampecaris obanensis and Archidesmus sp. from the late Silurian (425 million years ago) of Kerrera . There are also other millipedes, centipedes , and trigonotarbid arachnoids known from Ludlow (420 million years ago). Predatory invertebrates would indicate that simple food webs were in place that included non-predatory prey animals. Extrapolating back from Early Devonian biota, Andrew Jeram et al. in 1990 suggested

1512-627: The Tethys, the Proto-Tethys and Paleo-Tethys , the Rheic Ocean , the Iapetus Ocean (a narrow seaway between Avalonia and Laurentia), and the newly formed Ural Ocean . The Silurian period was once believed to have enjoyed relatively stable and warm temperatures, in contrast with the extreme glaciations of the Ordovician before it and the extreme heat of the ensuing Devonian; however, it is now known that

1566-415: The beginning of the century. In 1872 Charles J. Werner reopened a quarry, which since his death in 1888 has been operated by his sons, who purchased in 1890 a second quarry, which had previously been opened by Robert Wilson. These quarries became of some importance in 1893, when one of them is spoken of as the principal Ellicott City quarry, although it is now producing little or no building stone except during

1620-493: The conflict by defining a new Ordovician system including the contested beds. An alternative name for the Silurian was "Gotlandian" after the strata of the Baltic island of Gotland . The French geologist Joachim Barrande , building on Murchison's work, used the term Silurian in a more comprehensive sense than was justified by subsequent knowledge. He divided the Silurian rocks of Bohemia into eight stages. His interpretation

1674-455: The edge of the continental shelf) can be identified, and the highest Silurian sea level was probably around 140 metres (459 ft) higher than the lowest level reached. During this period, the Earth entered a warm greenhouse phase, supported by high CO 2 levels of 4500 ppm, and warm shallow seas covered much of the equatorial land masses. Early in the Silurian, glaciers retreated back into

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1728-461: The end of the Silurian, sea levels dropped again, leaving telltale basins of evaporites extending from Michigan to West Virginia, and the new mountain ranges were rapidly eroded. The Teays River , flowing into the shallow mid-continental sea, eroded Ordovician Period strata, forming deposits of Silurian strata in northern Ohio and Indiana. The vast ocean of Panthalassa covered most of the northern hemisphere. Other minor oceans include two phases of

1782-736: The exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution : vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods ( myriapods , arachnids and hexapods ) became fully terrestrialized. Another significant evolutionary milestone during

1836-469: The fall of the year when random rubble is quarried for local use. The output for the year 1896 did not aggregate over 200 perches . The most active quarry at the present is that operated by A. Weber. This quarry is situated on the Howard county side some distance below the station. The material has been furnished in recent years for some important buildings, as those of the Woman's College of Baltimore , but most of

1890-503: The first deep-boring bivalves are known from this period. Chitons saw a peak in diversity during the middle of the Silurian. Hederelloids enjoyed significant success in the Silurian, with some developing symbioses with the colonial rugose coral Entelophyllum . The Silurian was a heyday for tentaculitoids , which experienced an evolutionary radiation focused mainly in Baltoscandia, along with an expansion of their geographic range in

1944-670: The first period to see megafossils of extensive terrestrial biota in the form of moss -like miniature forests along lakes and streams and networks of large, mycorrhizal nematophytes , heralding the beginning of the Silurian-Devonian Terrestrial Revolution. However, the land fauna did not have a major impact on the Earth until it diversified in the Devonian. The first fossil records of vascular plants , that is, land plants with tissues that carry water and food, appeared in

1998-451: The global climate underwent many drastic fluctuations throughout the Silurian, evidenced by numerous major carbon and oxygen isotope excursions during this geologic period. Sea levels rose from their Hirnantian low throughout the first half of the Silurian; they subsequently fell throughout the rest of the period, although smaller scale patterns are superimposed on this general trend; fifteen high-stands (periods when sea levels were above

2052-470: The granite itself, their irregular outlines contrast sharply with the lighter background. Mathews described the granite itself as follows: The appearance of the Woodstock granite is well represented in ( the polished slab shown at right ) which reproduces the polished surface in natural size. The color of the rock is bright gray, with something of a luster imparted by the quartz and the unaltered feldspars ,

2106-457: The lack of tillites in the middle to late Silurian make this explanation problematic. The Silurian period has been viewed by some palaeontologists as an extended recovery interval following the Late Ordovician mass extinction (LOME), which interrupted the cascading increase in biodiversity that had continuously gone on throughout the Cambrian and most of the Ordovician. The Silurian was

2160-402: The late-Ordovician glaciation. The southern continents remained united during this period. The melting of icecaps and glaciers contributed to a rise in sea level, recognizable from the fact that Silurian sediments overlie eroded Ordovician sediments, forming an unconformity . The continents of Avalonia , Baltica , and Laurentia drifted together near the equator , starting the formation of

2214-478: The latter often giving an additional faint pink tone. The mica occurs in evenly disseminated fine black flakes which emphasize the grain of the rock and only slightly subdue the bright fresh aspect of the stone. The size of the constituent grains which varies from 0.05-0.2 inches in length, and from 0.01-0.10 inches in breadth, for quartz and feldspar, is little marred by the less resistant mica wearing away and leaving small depressions, that are scarcely discernible to

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2268-529: The local quarrying industry circa 1820." The 1898 account of Edward B. Mathews of the Maryland Geological Survey of the quarries at Granite (formerly known as Waltersville) begins with boulders attracting the attention of "several enterprising men from New Hampshire," (Sweatt, Putney, and Riddle) who commenced quarrying operations about 1832-33, and supplied stone to the Baltimore and Ohio Railroad. He continued: Although prospecting has been carried on ever since, only two ledge quarries have been discovered, viz.:

2322-556: The mass extinction's aftermath, but expanded their range afterwards. The most abundant brachiopods were atrypids and pentamerides; atrypids were the first to recover and rediversify in the Rhuddanian after LOME, while pentameride recovery was delayed until the Aeronian. Bryozoans exhibited significant degrees of endemism to a particular shelf. They also developed symbiotic relationships with cnidarians and stromatolites. Many bivalve fossils have also been found in Silurian deposits, and

2376-507: The material seems to be used for Belgian blocks , curbing and macadam . In 1973, M. W. Higgins reported a radiometric ( Rb-Sr age ) of 425 Ma, which placed the Ellicott City Granodiorite in the Silurian . In 1998, A. A. Drake revised the age to Ordovician based on the granodiorite's relationship with the Woodstock Quartz Monzonite . Silurian The Silurian ( / s ɪ ˈ lj ʊər i . ən , s aɪ -/ sih- LURE -ee-ən, sy- )

2430-466: The most important stone structures in the United States at the time of its construction, the quarries evidently were worked only to meet local demands. In fact they have never since been of such relatively great importance. Dr. David Dale Owen , indeed, while studying the various building stones of Maryland at Cockeysville , Woodstock and Port Deposit , with the view of gaining all the information for

2484-579: The naked eye. The polished surfaces, such as are represented in ( the same figure ), are darker than the rough or ashlar finished stone. Hopson reported the chemical composition (by %) of the Woodstock Quartz Diorite from the "Sylvan Dell Quarry" (probably the Waltersville Quarry) in Granite, Maryland, as follows: The Walters/Blunt family of Waltersville (later Granite, Maryland) "founded

2538-515: The owner, Captain Alexander Walters, to whose family this quarry has belonged for more than a century. It is called in the lease and is still known as the Waltersville quarry, although the name of the village of Waltersville was changed to Granite about 1873-74, when the first post-office at the place was established. The lessees went to work vigorously, and besides many other improvements, built

2592-447: The rock, as shown in (the figure) ." Mathews continued with a description of their historical importance: The time of opening these quarries dates back probably into the last of the 18th century, but the details are entirely wanting. The beautiful appearance of some of the more uniformly porphyritic specimens early attracted attention, and in the earliest works which we have on this area, that by Dr. Hayden published in 1811, mention

2646-488: The second half of the Silurian Period. The earliest-known representatives of this group are Cooksonia . Most of the sediments containing Cooksonia are marine in nature. Preferred habitats were likely along rivers and streams. Baragwanathia appears to be almost as old, dating to the early Ludlow (420 million years) and has branching stems and needle-like leaves of 10–20 centimetres (3.9–7.9 in). The plant shows

2700-507: The shallow Silurian seas and lakes of North America; many of their fossils have been found in New York state . Brachiopods were abundant and diverse, with the taxonomic composition, ecology, and biodiversity of Silurian brachiopods mirroring Ordovician ones. Brachiopods that survived the LOME developed novel adaptations for environmental stress, and they tended to be endemic to a single palaeoplate in

2754-453: Was described in 1898 as "perhaps the best granite in Maryland for general building purposes" by Edward B. Mathews of the Maryland Geological Survey. Mathews described the mapped extent of the granite and inclusions of gneiss within it as follows: The granite mass as indicated by the map forms a more or less oval, isolated area of granite extending scarcely two miles northeast and southwest and

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2808-634: Was examining fossil-bearing sedimentary rock strata in south Wales in the early 1830s. He named the sequences for a Celtic tribe of Wales, the Silures , inspired by his friend Adam Sedgwick , who had named the period of his study the Cambrian , from a Latin name for Wales. Whilst the British rocks now identified as belonging to the Silurian System and the lands now thought to have been inhabited in antiquity by

2862-409: Was questioned in 1854 by Edward Forbes , and the later stages of Barrande; F, G and H have since been shown to be Devonian. Despite these modifications in the original groupings of the strata, it is recognized that Barrande established Bohemia as a classic ground for the study of the earliest Silurian fossils. With the supercontinent Gondwana covering the equator and much of the southern hemisphere,

2916-406: Was succeeded by his son Frederick, and the firm became Sumwalt & Green, who conducted the business until 1865, when Attwood Blunt, whose wife owned the property, took charge and continued the business until 1871, when the quarry was leased to Ansley Gill and James McMahon. After a lapse of about sixteen years, the firm was dissolved by the death of McMahon. Mr. Gill continued the business alone for

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