A depth-dose curve was obtained for a ⁹⁰4SR- ⁹⁰Y beta source using a fine grain TL phosphor to measure the absorbed dose, aluminium absorbers being interposed between the source and the detector; the curve went through a maximum at an absorber thickness of about 40 mg cm^-2. This curve was then used to predict the average dose rate to various thicknesses of calcium fluoride which has a similar absorption characteristic to aluminium; these values were compared with experimentally determined dose rates. This work was done in connection with thermoluminescence dating of flint and calcite in archaeology and geology.