How Unfold works

Why flat maps get size wrong

Most online maps use the Mercator projection. It keeps shapes and directions right, which makes it great for navigation, but it stretches everything more and more toward the poles. Greenland looks as big as Africa, though Africa is about 14 times larger.

On a globe, nothing is stretched. Unfold lets you peel the globe open into the flat map and back, so you can watch the stretching happen.

How the copies keep their true size

When you drag a copy of a country, it is moved across the sphere, not across the flat map, so its shape and area stay exactly true. On the flat map it then grows or shrinks with the map's stretching, which is the whole point: it shows how much the map distorts each place.

Deep time

Deep time moves today's land along with the tectonic plates it sits on, back to 400 million years ago, and shows the geography of each era: land, shallow seas, mountains and ice. Sea levels change too, so you can see how much of today's land was under water at each time.

It uses a published scientific plate model and the ancient geography built for it. Plates are treated as rigid, so small gaps or overlaps appear where real continents stretched or crumpled. Country borders and names are shown on the plates for orientation only; those countries did not exist then.

Sources and credits

• Country and coastline outlines, states and provinces, city footprints, glaciers: Natural Earth (public domain). City footprints come from early-2000s satellite data, so fast-growing cities are shown smaller than they are today.
• Historical empires: Cliopatria, Seshat Global History Databank, CC BY 4.0.
• Plate motions: Matthews et al. 2016, Global and Planetary Change 146. Ancient geography: Cao et al. 2017, Biogeosciences 14. Both via EarthByte, CC BY 4.0.
• Elevation and shaded relief: NOAA ETOPO1, NOAA National Centers for Environmental Information (public domain).
• Satellite and night imagery: NASA Blue Marble and Black Marble, via NASA GIBS (ESDIS).

Privacy

Unfold has no accounts and sets no cookies. What you place on the map is kept only in your own browser. A shared link contains just the view you chose to share.