Inside a volcano how do the slanted layers of hardened lava get there

This is a build up of lava which came out of the volcano in previous eruptions, once this lava came out of the volcano it cooled and hardened, over many eruptions layers of hardened volcanic rock will form. The layers are slanted as gravity acts on the lava so it flows down and a little further from the cone.

1b. convection2f. the same