As a species, our first tools were made of stone, and ironically it is our contemporary tools, modes of production, and manufacturing processes that have accelerated our move toward extinction as a species. We are at the mercy of climate change and the planet is sweating us out in a hot fever. In the deep past, glaciers moved granite boulders across the ground, scouring and marking the terrain before depositing these boulders erratically in the landscape. These glacial erratics dot the landscape and stand as markers of past geologic activity, much like the way we use granite tombstones to mark the past activity of a human life. But for the glacier, granite erratics are much more than mere markers; these stones are also the mark makers, the very tool used by a glacier to shape the landscape in the process of moving the stone. Might this be adapted to our conception of tombstones as latent objects? By recasting the tombstone as a potential mark making tool for a glacier in the deep future, tombstones can be reframed as our final stone tools and we can predict the future landscape patterns that our cemetery fields of stones might leave behind after the next ice age (should the planet be so lucky). The slow advancing and retreating motion of a glacier grinds grooves into bedrock much like the use of a carpenter’s hand plane to flatten and flute details in wood. Lines of Descent takes this idea and iterates the development of a series of progressively complex hand planes with strange granite blades fashioned in the shape of common tombstone profiles to produce a series of landscape models to help visualize a future terrain that will be formed by the memorial stones we leave behind. The tombstone markers of familial lines meet the iterative lines of drift in the developmental process of tool making to predict what new lines our memorials will leave in the landscape after the descent of humanity in the deep future.