For instance, if you are thinking - I have a strong interest in physics/chemistry - can I combine such disciplines with geology and still be able to find employment as a geologist?

Geology is a broad field and allows for combining different disciplines - such as physics, chemistry, mathematics, and biology with geology. In fact one of the main reasons students are drawn to geology is because they can easily merge their interests in most scientific fields with geology - an approach that is well-suited for solving environmental problems as the study of the Earth also involves understanding its physics, chemistry and biology!