Amagma that contains 42 percent silica is referred to as

Magma (from the Latin magma and this from the Greek μάγμα, "pasta") is the name given to the masses of molten rocks from the interior of the Earth or other planets. They are usually composed of a mixture of liquids, volatile and solids.

 The most common magmas respond to three main types: basaltic, andesitic and granitic.

 Basaltic magmas: can be tolelic, low in silica (<50%) and produced in the back, or alkaline, rich in sodium and potassium, produced in areas of the interior of tectonic plates. They are the most common.

In line with other previous and contemporaneous proposals, in 1912 the meteorologist  alfred wegener  amply described what he called continental drift, expanded in his 1915 book the origin of continents and oceans and the scientific debate started that would end up fifty years later in the theory of plate tectonics.