After the U.S. Geological Survey was created in 1879, he was appointed to the position of Senior Geologist and worked for the USGS until his death (including a term as acting director).

Gilbert's calculations showed that the crater's volume and the debris on the rim were roughly equal, and that there were no magnetic anomalies.

Gilbert is considered one of the giants of the subdiscipline of geomorphology, having contributed to the understanding of landscape evolution, erosion, river incision, and sedimentation.

He was a planetary science pioneer, correctly identifying lunar craters as caused by impacts, and carrying out early impact-cratering experiments.

[7] He coined the term sculpture for a pattern of radial ridges surrounding Mare Imbrium on the moon, and correctly interpreted them in 1892 as ejecta from a giant impact.

Gilbert's wide-ranging scientific ideas were so profound that the Geological Society of America published GSA Special Paper 183 on his research (Yochelson, E.L., editor, 1980, The Scientific Ideas of G.K. Gilbert, fourteen separate biographical chapters, 148 pages).