Here's a breakdown of how they form:

1. Magma Accumulation: Molten rock (magma) rises from deep within the Earth's mantle. It accumulates in a chamber beneath the Earth's crust.

2. Pressure Build-up: The magma exerts pressure on the surrounding rock.

3. Crustal Uplift: As pressure increases, the crust above the magma chamber begins to bulge upward.

4. Eruptions: Eventually, the pressure becomes too great, and the magma erupts through the surface, creating a volcano.

5. Conical Shape: Repeated eruptions build up layers of lava, ash, and other volcanic debris, forming the characteristic cone shape of a stratovolcano.

Examples of famous stratovolcanoes include Mount Fuji (Japan), Mount Vesuvius (Italy), and Mount Rainier (USA).