A method and apparatus for real time, on-site detection and analysis of caminant in soil, the invention continuously measures and records specific spectral properties of potentially contaminated soil along a typically vertical profile as a soil penetrating probe of the invention penetrates the soil. The probe is fitted with a light transparent window and a light source disposed internally of the probe. Light from internally of the probe passes through the window and is reflected back through the window from the soil as the probe passes through the soil, the light reflected from the soil back through the window being collected by a fiber optic link within the probe. The collected light is then transmitted through the fiber optic link to the surface for measurement and recordation of spectral distribution and intensity. Determination of the type and amount of contaminant is possible by comparison of the spectral signature of the soil to standards prepared by adding known concentrations of specific contaminant to soil similar to the soil found on the test site. The invention thus allows rapid on-site determination of the location, depth and quantity of contaminant in soils and particularly soils in waste disposal sites. 2