<P> The Himalayas, the world's tallest mountain range, are assumed to have been formed by the collision of two major plates . Before uplift, they were covered by the Tethys Ocean . </P> <P> Depending on how they are defined, there are usually seven or eight "major" plates: African, Antarctic, Eurasian, North American, South American, Pacific, and Indo - Australian . The latter is sometimes subdivided into the Indian and Australian plates . </P> <P> There are dozens of smaller plates, the seven largest of which are the Arabian, Caribbean, Juan de Fuca, Cocos, Nazca, Philippine Sea, and Scotia . </P> <P> The current motion of the tectonic plates is today determined by remote sensing satellite data sets, calibrated with ground station measurements . </P>

Who was it that suggested that the crust is broken up into plates called tectonic plates