The location source of magma is typically found in the Earth's mantle, just beneath the crust. Magma forms when rocks in the mantle partially melt due to high temperatures and pressure conditions. This molten rock then rises toward the Earth's surface because it is less dense than the surrounding solid rock, eventually leading to volcanic activity when it erupts. So, the mantle acts as the main source region where magma originates before moving upward through the crust.