Deep time

What it does

Deep time shows reconstructed coastlines for a chosen moment in the past. Move the slider back through hundreds of millions of years. The coastlines are computed by rotating tectonic plates in the browser.

Two plate models are included, so their differences can be compared.

Use Deep time for questions a static palaeogeographic map cannot answer: when an ocean opened, what was next to what, or how long two coastlines were joined.

Using it

1. Open the tool and move the slider. The coastlines redraw for that age.
2. Switch models to see how much of the picture is model rather than fact.

The layer outlives the panel. Closing the tool leaves the coastlines on the map, because closing is how you get the map to yourself. You can then measure the ocean between two continents, ask the info tool about a polygon, or print what is on screen. From then on it is an ordinary layer, and the legend is where you turn it off.

In your own map

Add deeptime to a toolbar and point it at a plate model with data, plus the ages it covers. Model data is a config asset, resolved relative to the config file, so it lives beside the config rather than inside webmapx.

A map with no coastline layer gets one. A map that already draws the same computed source reuses it.

Extending it

Reconstructed geometry is cut on the sphere before it leaves the tool. Watch ring winding, degenerate rings, and caps closed exactly along ±90. Each can make a polygon render inside out or cover the map.

Check an equirectangular and an equal-area projection when changing this code.