It is not, as you mentioned, becuase of map error. In order to qualify as a continent a landmass must meet certain criteria:
1: They must have their own river and drainage system which drains into the ocean. Europe has several of its own, so does asia
This is the most important one: Each continent must have its own shield. Shield is a geologic term for the underlying layer of bedrock. It consists of a slope at either end, and a large flat area in the middle, which rises above sea level. Europe is situated on one shield and asia is situated on an entirely different shield.
This hardly seems relevant. By that argument, California and northern Ohio are on different continents than Kansas, since Kansas’s drainage is into the Gulf of Mexico via the Missorissippi River, northern Ohio’s is into the St. Lawrence River via the Great Lakes, and California’s is into the Pacific via various rivers. If we ignore minor anomalies like Lake Isa and Chicago’s sanitary canal, then North America has at least three major complete and separate drainage systems.
He said that the drainage systems must be separate, not that separate drainage means different continents. It’s one of those necessary but insufficient conditions.
Though one might look at how the California coast fits with those definitions.
So I assume Asia isn’t a continent, because India and Arabia are on separate tectonic plates. However, India and Australia lie on the same tectonic plate; and Europe, most of Asia and North America share a plate. Map.
A shield or craton typically has a slightly narrower definition than a tectonic plate, but it still doesn’t make a valid definition of a continent. According to the Hutchinson Encyclopedia a shield or craton: “The relatively stable core of a continent that is not currently affected by tectonics along plate boundaries.” L Don Leet’s Physical Geology defines a craton as “Relatively immobile part of the earth, generally large central portion of a continent.” Do you see some circularity here? A continent is a craton and a craton is a continent.
It is commonly accepted that linguistic, cultural and the very convenient divider in the Ural Mountains is why Europe and Asia are considered seperate continents.
No, that’s not right. The Earth’s crust is composed of roughly twelve separate plates that ride on the partially molten mantle and are driven around by convective flow. The crust is definitely not one single landmass.