A system and method for making downhole measurements utilize a neutron source (12) to create a marker (122) in an underground formation (2), a nuclear radiation detector (D, 124)) to detect gamma and/or other nuclear radiation emitted by the marker (122) and a downhole drilling progress monitoring unit (20) which generates real time information about incremental depth and/or associated Rate Of Penetration (ROP) of an automated or other drilling assembly (4) based on detection of the nuclear radiation and an axial distance L between the neutron source (120) and the nuclear radiation detector (D, 124) without requiring transmission of the real time incremental depth and/or ROP data to surface equipment via a complex wired or wireless data transmission system.