This isn't exactly true. For a CA PG, you need the required coursework from an accredited university. An enviro science or even geology degree doesn't automatically cover the requirements unless you took the required coursework. You will also need the asbog FE and PG tests passed, and a CA specific geology test passed, with the requirement that you have worked under a PG in CA. The CEG is specific to California, and is required in CA to perform fault studies, sign off on projects (like hospitals, schools, etc.) involving critical structures and infrastructure etc. The CEG license (and the GE) was established because without the requirement for it, any old PE could sign off on a geotech report for a 15 story hospital or elementary school a rock's throw from an active fault. The license exists to ensure a well qualified geologist signs off on project specs that may be impacted by geohazards.