Test units open wider windows into the archaeological deposits than shovel tests provide. Sometimes these larger, more controlled excavations even reveal archaeological features (see drawing and photo above). By gradually removing the soil with a flat shovel, the field crew can identify the natural stratigraphy and keep separate drawings, notes, and bags of artifacts from each layer. The archaeologist (right) tosses soil from the test unit into the sifting screen hanging from the frame. The soil is then passed through the wire mesh of the screen for easy recovery of artifacts.