Reconstruction of the environment around 400 million years ago in which the sediments of the Brownstones were forming. This is a terrestrial environment dominated by an extensive network of rivers crossing floodplains. Overall the planet was in a greenhouse (hot) phase. The rivers carried sediment from eroding high ground to the north-west – the Caledonide mountain chain (see below) that formed during the Silurian as the Iapetus Ocean was destroyed and Avalonia (out bit of crust) was sutured to Laurentia.