What’s Down There? Activity Source: SEED (Shlumberger Excellence in Educational Development) with permission. Throughout the Earth’s history, the cycle of erosion and deposition by water and wind has added layer upon layer of rock, soil, and organic material to the surface. Most sedimentary rock is beneath the surface. To learn about sedimentary rock layers that we cannot see, geoscientists drill and bring up core samples of rock layers. Information from core samples, combined with that from other imaging techniques, allows geoscientists to map the depth and thickness of sedimentary rock layers below the surface. [Read More]