Question: When did the mountain building period that created the Taconic unconformity end?

Context paragraphs:
Robert Graham House: Robert Graham House is a historic home located near Newark, New Castle County, Delaware.  The house consists of sections built during three main periods.  The log, central core dates to about 1790, and was first constructed as a one-story building with a loft and later raised to a full two stories.  The two-story, stone western section was added about 1819.  The final building period occurred in the mid-1930s with two frame additions, a two-story, frame, rear wing behind the stone section, and a one-story, frame wing east of the log section, with a three-car garage at the basement level.  Because the house is banked into the hill, a full three levels of the stone end, including the basement, are exposed.  The stone section features a shed-roofed, front porch on a high stone foundation.  Also on the property are a contributing stone terrace (c. 1947) and a stone wall from the mid-1930s.

Taconic orogeny: The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England.  A great mountain chain formed from eastern Canada down through what is now the Piedmont off the East coast of the United States.  As the mountain chain eroded in the Silurian and Devonian periods, sediments from the mountain chain spread throughout the present-day Appalachians and midcontinental North America.

Acadian orogeny: The Acadian orogeny is a long-lasting mountain building event which began in the Middle Devonian, reaching a climax in the early Late Devonian.  It was active for approximately 50 million years, beginning roughly around 375 million years ago, with deformational, plutonic, and metamorphic events extending into the Early Mississippian.  The Acadian orogeny is the third of the four orogenies that created the Appalachian orogen and subsequent basin.  The preceding orogenies consisted of the Potomac and Taconic orogeny, which followed a rift/drift stage in the Late Neoproterozoic.  The Acadian orogeny involved the collision of a series of Avalonian continental fragments with the Laurasian continent.  Geographically, the Acadian orogen extended from the Canadian Maritime provinces migrating in a southwesterly direction toward Alabama.  However, the Northern Appalachian region, from New England northeastward into Gaspé region of Canada, was the most greatly affected region by the collision.

Church of St Nicholas, Trellech: The Church of St Nicholas, Trellech, Monmouthshire is a parish church with its origins in the 14th century.  The historical and architectural evidence suggests that it was constructed largely in a single building period c.1300.  The style is Decorated Gothic.  The church was extended and repaired in the 18th century, and underwent two major reconstructions in 1893 and 1992.  An "exceptionally fine and well preserved medieval church", it is a Grade I listed building.  It remains an active parish church in the parish of Trellech and Penallt.

Laramide orogeny: The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago.  The exact duration and ages of beginning and end of the orogeny are in dispute.  The Laramide orogeny occurred in a series of pulses, with quiescent phases intervening.  The major feature that was created by this orogeny was deep-seated, thick-skinned deformation, with evidence of this orogeny found from Canada to northern Mexico, with the easternmost extent of the mountain-building represented by the Black Hills of South Dakota.  The phenomenon is named for the Laramie Mountains of eastern Wyoming.  The Laramide orogeny is sometimes confused with the Sevier orogeny, which partially overlapped in time and space.

History of Canadian newspapers: There were five important periods in the history of Canadian newspapers' responsible for the eventual development of the modern newspaper.  These are the "Transplant Period" from 1750–1800, when printing and newspapers initially came to Canada as publications of government news and proclamations; followed by the "Partisan Period from 1800–1850," when individual printers and editors played a growing role in politics.  The "Nation Building Period from 1850–1900," when Canadian editors began the work of establishing a common nationalistic view of Canadian society.  The "Modern period" from 1900 to 1980s saw the professionalization of the industry and the growth of chains.  "Current history" since the 1990s saw outside interests take over the chains, as they faced new competition from the Internet.

Taconic unconformity: The Taconic unconformity is a major unconformity created during the Taconic orogeny, exposed from eastern New York State to the Gaspe peninsula.  The orogeny was a long one that comprised multiple bursts; it primarily dated to the end of the Ordovician, and the underlying rocks are primarily this age.  It is overlain by Silurian and Devonian metasediments.

Sonoma orogeny: The Sonoma orogeny was a period of mountain building in western North America.  The exact age and structure of the Sonoma orogeny is controversial.  The orogeny is generally thought to have occurred during the Permian / Triassic transition, around 250 million years ago, following the Late Devonian Antler orogeny.  The Sonoma orogeny was one of a sequence of accretionary events along the Cordilleran margin, possibly caused by the closure of the basin between the island arc of Sonomia and the North American continent.  Evidence of this event has been reported throughout western North America, but most distinctly in northwest Nevada.

Shield (geology): A shield is generally a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas.  In all cases, the age of these rocks is greater than 570 million years and sometimes dates back 2 to 3.5 billion years.  They have been little affected by tectonic events following the end of the Precambrian, and are relatively flat regions where mountain building, faulting, and other tectonic processes are greatly diminished compared with the activity that occurs at the margins of the shields and the boundaries between tectonic plates.

Qingdao–Rongcheng Intercity Railway: Qingdao–Rongcheng Intercity Railway is a high-speed railway located in China's, Shandong Province.  It travels along the Shandong Peninsula connecting to Qingdao and Rongcheng.  Line length is 298.842 km (containing a total length of sidings, spurs and depots etc. of 335 km ).  The design speed is based on 250 km/h service.  However, it has been reserved for the line to be upgraded, if warranted, to 300 km/h .  Construction consisted of a three-month preparation period, a building period of 27 months and with a joint testing and commissioning period of six months.  On December 28, 2014, the Qingdao–Rongcheng Intercity Railway opened from Jimo to Rongcheng.  The whole line is opened on November 16, 2016. 。

Supporting paragraphs: Taconic unconformity Taconic orogeny
Answer: 440 million years ago