Acadian orogeny in the context of Grenville orogeny

The Highland Boundary Fault is a major fault zone that traverses Scotland from Arran and Helensburgh on the west coast to Stonehaven in the east. It separates two different geological terranes which give rise to two distinct physiographic terrains: the Highlands and the Lowlands, and in most places it is recognisable as a change in topography. Where rivers cross the fault, they often pass through gorges, and the associated waterfalls can be a barrier to salmon migration.

The fault is believed to have formed in conjunction with the Strathmore syncline to the south-east during the Acadian orogeny in a transpressive regime that caused the uplift of the Grampian block and a small sinistral movement on the Highland Boundary Fault.

The Iapetus Ocean (/aɪˈæpɪtəs/; eye-AP-ih-təs) existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). It was in the Southern Hemisphere, between the paleocontinents of Laurentia, Baltica and Avalonia. The ocean disappeared with the Acadian, Caledonian and Taconic orogenies, when these three continents joined to form one big landmass called Euramerica. The "southern" Iapetus Ocean has been proposed to have closed with the Famatinian and Taconic orogenies, meaning a collision between western Gondwana and Laurentia.

Because the Iapetus Ocean was positioned between continental masses that would at a much later time roughly form the opposite shores of the Atlantic Ocean, it can be seen as a sort of precursor of the Atlantic, and the process by which it opened shares many similarities with that of the Atlantic's initial opening in the Jurassic. The Iapetus Ocean was therefore named for the titan Iapetus, who in Greek mythology was the father of Atlas, after whom the Atlantic Ocean was named.

The following is a list of subranges within the Appalachian Mountains, a mountain range stretching ~2,050 miles from Newfoundland and Labrador, Canada to Alabama, US. The Appalachians, at their initial formation, were a part of the larger Central Pangean Mountains along with the Scottish Highlands, the Ouachita Mountains, and the Anti-Atlas Mountains. The modern ranges were formed and/or deformed by the Acadian, Caledonian, Alleghenian, Mauritanide and Variscan orogenies with the Alleghenian orogeny being the most notable to the modern Appalachians.

The Appalachians are also subdivided by a number of large plateaus and additional subplateus. These are commonly not considered subranges although they do contain some features referred to as mountains which are assigned to both their geographic "range" and the more general Appalachian Mountains. These plateaus, such as the Allegheny Plateau, are considered provinces of the Appalachian Highlands and the mountains assigned to them are instead considered pieces of dissected plateaus.

The Caledonian orogeny was a mountain-building cycle recorded in the northern parts of the British Isles, the Scandinavian Caledonides, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occurred from the Ordovician to Early Devonian, roughly 490–390 million years ago (Ma). It was caused by the closure of the Iapetus Ocean when the Laurentia and Baltica continents and the Avalonia microcontinent collided.

The orogeny is named for Caledonia, the Latin name for Scotland. The term was first used in 1885 by Austrian geologist Eduard Suess for an episode of mountain building in northern Europe that predated the Devonian period. Geologists like Émile Haug and Hans Stille saw the Caledonian event as one of several episodic phases of mountain building that had occurred during Earth's history. Current understanding has it that the Caledonian orogeny encompasses a number of tectonic phases that can laterally be diachronous, meaning that different parts of the mountain range formed at different times. The name "Caledonian" can therefore not be used for an absolute period of geological time, it applies only to a series of tectonically related events.