The dynamics of heat have played a formative role in the shaping of the Earth, most notably in its self-differentiation into distinctive spheres or layers. The ability to work with fire has a special role when it comes to the ways in which the genus Homo has interacted with the structural layering of our planet, both recently and over evolutionary timescales. This chapter explores how humans have developed fire-centered practices to engage with soil and its living communities, with the voluminous layers of rock that comprise the Earth’s crust, and—in less direct ways—with the seething, unlivable reaches of the inner Earth. Such world-shaping fiery practices require intensive learning and utmost care, as both combustion and its prohibition can have disastrous consequences for Earth systems.