We have examined the optical absorption and spin-resonance signal characteristics of thin layers of silicon damaged by an abrasive process at room temperature. We find an Urbach-like dependence of the subgap absorption and a g=2.0055 isotropic spin-resonance signal characteristic of silicon dangling bonds. Changes in the optical and spin-resonance data caused by thermal anneals in air, or in atomic hydrogen, indicate that direct electronic transitions of the dangling bond defect are not responsible for the observed optical-absorption spectra. The doping level dependence of these spectra is consistent with the hypothesis that electronic transitions arising from disorder-induced band-tail states cause the subgap absorption.