The Ouachita orogeny was a mountain building event that resulted in the folding and faulting of strata currently exposed in the Ouachita Mountains.
 The more extensive Ouachita system extends from the current range in Arkansas and Oklahoma southeast to the Black Warrior Basin in Alabama and to the southwest through the Llano, Marathon, and Solitario uplifts in Texas on into Coahuila and Chihuahua in Mexico.
Tectonic uplift is the portion of the total geologic uplift of the mean Earth surface that is not attributable to an isostatic response to unloading.
 While isostatic response is important, an increase in the mean elevation of a region can only occur in response to tectonic processes of crustal thickening (such as mountain building events), changes in the density distribution of the crust and underlying mantle, and flexural support due to the bending of rigid lithosphere.
Mountain formation refers to the geological processes that underlie the formation of mountains.
 These processes are associated with large-scale movements of the Earth's crust (tectonic plates).
 Folding, faulting, volcanic activity, igneous intrusion and metamorphism can all be parts of the orogenic process of mountain building.
 The formation of mountains is not necessarily related to the geological structures found on it.
Basin and range topography is an alternating landscape of parallel mountain ranges and valleys.
 It is a result of crustal extension/stretching (extensional tectonics) of the lithosphere (crust and upper mantle) due to mantle upwelling, gravitational collapse, crustal thickening, or relaxation of confining stresses.
 Crustal extension causes the thinning and deformation of the upper crust in an orientation perpendicular to the direction of extension.
 As the plates pull apart, they thin allowing the hot mantle to rise close to the surface.
 When the crust is extended it fractures along a fault plane, creating a series of long parallel normal faults. Between these normal faults are blocks, which subside, get uplifted or tilted.
 This is known as block faulting.
 Basins are formed due to subsidence of a block, while the blocks adjacent to the subsidence gets uplifted creating ranges.
 Normal faults are on both sides the blocks; creating alternating elevated or subsided blocks, otherwise known as horst and graben.
 Basins and ranges can also be formed by blocks that are tilted causing one side to subside while the other side gets uplifted.
 These only have one side with a normal fault, this is known as tilted block faulting.
 Extension causes the plate to stretch, fracture and thin.
 Mountains rise and valleys drop, over a long period of time creating what we see as basin and range topography.
In probability theory, the complement of any event "A" is the event [not "A"], i.e. the event that "A" does not occur.
 The event "A" and its complement [not "A"] are mutually exclusive and exhaustive.
 Generally, there is only one event "B" such that "A" and "B" are both mutually exclusive and exhaustive; that event is the complement of "A".
 The complement of an event "A" is usually denoted as "A′", "A" or "A ".
 Given an event, the event and its complementary event define a Bernoulli trial: did the event occur or not?
The Trans-Hudson orogeny or Trans-Hudsonian orogeny was the major mountain building event (orogeny) that formed the Precambrian Canadian Shield, the North American Craton (also called Laurentia), and the forging of the initial North American continent.
 It gave rise to the Trans-Hudson orogen (THO), or Trans-Hudson Orogen Transect (THOT), (also referred to as the Trans-Hudsonian Suture Zone (THSZ) or Trans-Hudson suture) which is the largest Paleoproterozoic orogenic belt in the world.
 It consists of a network of belts that were formed by Proterozoic crustal accretion and the collision of pre-existing Archean continents.
 The event occurred 2.0-1.8 billion years ago.
The Antler orogeny was an enigmatic tectonic event, that began in the early Late Devonian with widespread effects continuing into the Mississippian and early Pennsylvanian.
 Most of the evidence for this event is in Nevada but the limits of its reach are unknown.
 A great volume of conglomeratic deposits of mainly Mississippian age in Nevada and adjacent areas testifies to the existence of an important tectonic event, and implies nearby areas of uplift and erosion, but the nature and cause of that event are uncertain and in dispute.
 Although it is known as an orogeny (mountain building event), some of the classic features of orogeny as commonly defined such as metamorphism, and granitic intrusives have not been linked to it.
 In spite of this, the event is universally designated as an orogeny and that practice is continued here.
 This article outlines what is known and unknown about the Antler orogeny and describes three current theories regarding its nature and origin.
The Smartville Block, also called the Smartville Ophiolite, Smartville Complex, or Smartville Intrusive Complex, is a geologic terrane formed in the ocean from a volcanic island arc that was accreted onto the North American Plate during the late Jurassic (~160–150 million years ago).
 The collision created sufficient crustal heating to drive mineral-laden water up through numerous fissures along the contact zone.
 When these cooled, among the precipitating minerals was gold.
 Associated with the Western Metamorphic Belt of the Sierra Nevada foothills it extends from the central Sierra Nevada mountain range, due west, under a section of the Central Valley and California Coast Ranges, in northern California.
 The ophiolitic sequence found in this terrane is one of several major ophiolites found in California.
 Ophiolites are crustal rocks from the ocean floor that have been moved on land.
 Ophiolites have been studied extensively regarding the movement of crustal rocks by plate tectonics.
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.
The Mount Pleasant Caldera is a large eroded Late Devonian volcanic caldera complex, located in the northern Appalachian Mountains of southwestern New Brunswick, Canada.
 It is one of few noticeable pre-Cenozoic calderas, and its formation is associated to a period of crustal thinning that followed the Acadian orogeny in the northern Appalachian Mountains.

Question: After the formation associated to a period of crustal thining what amount of time did a long-lasting mountain building event occur?
Answer: 50 million years