Surface gamma-neutron gauges have been used to evaluate soil physical properties, mainly soil bulk density. However, their use for compacted soil layer detection is still not well understood. In this work, a surface gamma-neutron gauge was used to identify the presence of compacted layers in soil profiles. Variations of the gauge response were also investigated for layers located at different depths. The results showed that although this type of gauge yields an average value of the densities found along the gamma-ray path, the use of an algorithm permitted the transformation of gauge measurements into layer density values, which were in good agreement with gravimetric measurements. The application of the algorithm was found to yield the best results when there was a large difference in density between the compacted layers and the medium around them.