| Silurian period| 423 to 419 million years ago Geography of the
Ludlow The geography of the Ludlovian world is best known for
the on-going train wreck which began the assembly of Laurasia -
or actually "Laurasia I" since there are arguably two continents
by that name. By Ludlovian times, Baltica (including
Scandinavia, European Russia and parts of Northern Europe) had
collided with Laurentia (North America and Greenland). This
began the north to south closure of the Iapetus Ocean which had
previously separated the two. The western edge of Baltica was
subducted under the Laurentian continent, with drastic effects
in North America. These effects included the northern part of
the Acadian Orogeny, a string of new volcanoes stretching from
East Greenland (future home of Ichthyostega and other famous
fossils) down the Laurentian coast towards New York and
Pennsylvania. In the meanwhile, the microcontinent of Avalonia,
as well as bits and pieces of Southern Europe which had been
flaking off the Gondwanan landmass,