GeoGlobe

How to read this globe

Each continent is treated as a rigid plate. Moving through the timeline rotates those plates across the sphere, so you are watching the same pieces of crust travel rather than new shapes being drawn. Coastlines are modern ones. A real Devonian coastline sat far inland of these edges, because shallow seas flooded most continental interiors.

The poles stay fixed at the top and bottom of the sphere. Anything sitting there was, at that moment, polar: that is how the Sahara ends up under an ice sheet and Antarctica ends up covered in forest.

Land is coloured by what grew on it. Before the Devonian the only land plants were small relatives of liverworts and the first simple stemmed plants, so the land is drawn as bare rock. From the Devonian on, the colours follow climate belts fixed to the globe, so a continent changes colour as it drifts from one latitude to another. Today's globe shows actual forests, deserts, rivers and lakes. Red-brown patches mark ground that the rocks themselves show was arid, such as the Old Red Sandstone continent, whatever belt it sat in. Mountain ranges appear in the period that raised them, and pale blue patches are shallow seas that flooded a continent's interior. All of it is schematic.

Labels in capitals give the name a continent had at the time, and labels in italics name the oceans of the time. Small labels beginning with "now" mark ground you would recognise today: in the Permian, "now the Appalachian Mts." sits in the middle of Pangaea.

Markers are pinned to their plate, so a fossil site drifts with the ground it sits in. Each one describes the place then and what grows there now.

Animals lists the animals that mark each period, in the sea, on land and in the air. Click one to see where its fossils come from; the place drifts with its plate like any other marker.

Comparisons pairs up places that look alike and sorts them by whether they were once joined. Layers shows two rock columns in the same colours as the timeline; click a layer to see where that ground was when the rock was laid down.

Published reconstructions disagree with each other. Two research groups can place the same ground 10 to 20 degrees of latitude apart, and before about 200 million years ago no ocean floor survives to measure, so an arrangement rests on palaeomagnetism, which gives latitude but not longitude, and on matching rocks and fossils across continents. This globe solves one arrangement against palaeolatitude evidence and holds to it. Where a published latitude for a site differs from where this globe draws it, the site gives both figures.

The plate rotations and the published reconstructions they follow are listed under Reconstruction method, and the climate belts, arid patches, mountain ranges, shallow seas and ice sheets under Terrain. Everything else on the globe cites its sources in the panel beside it.

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