Geologists are probably disproportionately Republican due to ties to resource extraction industries such as oil. Same with chemists due to their work applicable for pharmaceutical and other industrial work. Biologists are probably more disproportionately Dem due to 1) creationism vs. evolution but also 2) biologists being more likely to be women.
Ironic that evolution being central to their work would make biologists more likely to be Democrats when my initial theory (though yours probably has more truth to it) was that geologists even deeper awareness of the age of the earth might contribute to them leaning R.