[[file:land-rigs_fig2.png|thumb|{{figure number|2}}Circulating system of a rig. (From <ref name=pt03r50>Whittaker, A., ed., 1985, Field geologists training guide: Boston, MA, IHRDC, 291 p.</ref>.)]] | [[file:land-rigs_fig2.png|thumb|{{figure number|2}}Circulating system of a rig. (From <ref name=pt03r50>Whittaker, A., ed., 1985, Field geologists training guide: Boston, MA, IHRDC, 291 p.</ref>.)]] |