Caledonian-Appalachian

Mountains

Lecture 17

© EarthStructure (2nd ed) 311/30/2014

Caledonian

and

Appalachian

orogenic belt

© EarthStructure (2nd ed) 411/30/2014

Caledonian Orogeny

The Caledonian orogeny was a mountain building era recorded in the

northern parts of the British Isles, Scandanavia, Svalbard, eastern Greenland and parts of north-central Europe

© EarthStructure (2nd ed) 511/30/2014

• Ordovician to

Early Devonian, roughly 490-390 million years

ago (Ma).

• Caused by the

closure of the Iapetus

Ocean when the

continents and terranes of La

urentia, Baltica and

Avalonia collided.

The Caledonian orogeny is named for Caledonia,

the Latin name for Scotland.

© EarthStructure (2nd ed) 611/30/2014 © EarthStructure (2nd ed) 611/30/2014

Cambrian paleogeography and Iapetus

Scotese

© EarthStructure (2nd ed) 711/30/2014

Zones of the Appalachian Orogen

© EarthStructure (2nd ed) 811/30/2014

Appalachian-Caledonian orogenic belt

© EarthStructure (2nd ed) 911/30/2014

© EarthStructure (2nd ed) 1011/30/2014

Ophiolite Obduction Table Mountain peridotite (Gros Morne, Newfoundland)

ultramafic peridotite forms a table-top plateau

The park's rock formations include oceanic crust and mantle rock (peridodite) exposed by the plate-teconic obduction

Peridotite lacks

the usual

nutrients required

to sustain most

plant life, hence

its barren

appearance.

The rock is very

low in calcium,

very high in

magnesium, and

has toxic amounts

of heavy metals.

Peridotite is also

high in iron, which

accounts for its

brownish colour.

© EarthStructure (2nd ed) 1111/30/2014

Appalachians

© EarthStructure (2nd ed) 1211/30/2014

Southern Appalachians

© EarthStructure (2nd ed) 1311/30/2014

Alleghanian (l. Paleozoic) thrusts

© EarthStructure (2nd ed) 1411/30/2014

Pangea

Scotese

© EarthStructure (2nd ed) 1511/30/2014

1 b.y. of plate motion

Scotese, 2004