The winter solstice occurs during the hemisphere's winter. In the Northern Hemisphere, this is the December solstice (usually 21 or 22 December) and in the Southern Hemisphere, this is the June solstice (usually 20 or 21 June).
The continental crust is made up of rocks that consist primarily of silica and alumina called the "sial". The next layer of the Earth is called the mantle.
