Abstract: A landfill liner is provided for protecting soil from contaminated waste. The landfill liner includes a unitarily extruded sheet having a flexible central support defining opposed substantially parallel top and bottom surfaces. A plurality of soil gripping protrusions project unitarily from the bottom surface of the central support. The soil gripping protrusions are pointed to grippingly engage the soil being protected, and are disposed in a staggered array to prevent furrowing of the soil to which the liner is applied. A plurality of supporting protrusions project unitarily from the top surface of the central support. The supporting protrusions include substantially blunted or planar top surfaces for supporting a top liner thereon. The supporting protrusions are configured to optimize the transmissivity of waste material flowing therebetween. Edge regions of the central support are substantially free of protrusions to enable face-to-face overlapping of edge regions of the central support on adjacent liners.