These diagrams
are schematic cross-sections through the Earth’s crust at two
different periods of geological time. The first is from the Ordovician
period (around 460 million
years ago) and shows the area that is now the Isle of Man lying
on the margin of a small landmass called Avalonia which in turn forms
part of the massive continent of Gondwana. North of Avalonia
is the Iapetus Ocean
which separates Gondwana
from the northern continent of Laurentia.
Iapetus Ocean 460 Million
years ago
100s-1000s
of kilometres
By the process of continental
drift, Avalonia gradually moved northwards and collided with Laurentia
approximately 410 million
years ago, as shown in the second diagram. This tectonic event
has crumpled the rocks and formed the Caledonian mountain range. These
mountains originally extended from North America to Scandinavia and
equalled the size of the present day Himalayas. The Manx uplands represent
part of the eroded remains of the mountains and most of the
folds and faults visible in the Manx Group originate from this
time.
Collision of Laurentia
and Avalonia forms Caledonian Mountains 410 million years ago
