~ 4.0 Ga. One of the first islands to form on the Earth. The picture shows a bright sunny day, but the atmosphere is likely to have been dark and smoggy. All land at this time was formed by volcanic activity, either from hot spots or subduction zones. Continents, even small ones, are still a distance in the future.

Evolutionary Rock Cycles

258

The Origins of Continents

The Earth began with no continents . . . Just small, scattered, isolated volcanicarcs . . .

265

Early Growth of Continents

. . . that grew with time, lots of time. About2 billion years worth into larger continents.

265

Volcanic Arcs Evolve into Microcontinents264

Numerous Collisions Over AboutTwo Billion Years Build the Cores

Of Modern Continents

Small volcanoes and microcontinents, moving across the earth are bound to collide, and stick together to form even larger continents. It was this process that built the large continents we see today. Without it most land masses would be about the size of a state, or perhaps a few states, islands really, like living on Madagascar or New Zealand.

http://ace.acadiau.ca/science/geol/rraeside/quizzes/worldmap3p.htm

We are so used to the world as it exists today that it can be hard to imagine anything else. For example, in the image below the continents stand out prominently (partly of course because they are brightly colored), and then there is the Pacific ocean. But, if we were to go back 3 to 4 billion years the world would not look like this. Instead it would have been covered mostly by ocean with small islands scattered here and there, like the ones circled below. Imagine a world where the biggest land masses are only the size of Fini, or New Zealand, or at best Borneo and New Guinea.

Fiji

New Zealand

Hawaii

Borneo

New Guinea

United Plates of North America261

Stage Four2. 39 – 2.33

Stage One4.0 – 3.0

Stage Two2.7 – 2.5

Stage Three2.7 – 2.5

Constructing The Heart Of the North AmericaContinent

Stage Five1.8 – 1.7 Stage Six

1.8 – 1.6

262 & 266

All the continents grew bythese processes.

261

North America at 1.6 billion years ago. Finally a solid core.

Supercontinent Cycles

So, think abouthow such aplanetworks

Rodinia SupercontinentFrom about 1.2 billion to 600 million

years ago

273

Pangaea SupercontinentFrom about 320 million to 175 million

years ago

257

Cycles Within Cycles Within Cycles

Leading to the Earth as it Exists today