Bryn Mawr, Smith, and Mt Holyoke are probably the best known for geology. They should all have good-sized departments with coverage of paleontology. You could confirm this by checking faculty biographies on the web.
Bryn Mawr is in the Bi-College Consortium with Haverford, a coed school just a few minutes away. Bi-College students can take classes or declare a major at either school. Haverford doesn’t have a geology program, so any Haverford student that wants to study or major in geology has to do it at Bryn Mawr. This means that Bryn Mawr geology classes typically include a noticeable number of guys, which may or may not be what you are looking for in a women’s college experience.
Smith and Holyoke are in the Five-College Consortium with Amherst College, UMass-Amherst, and Hampshire College, all of which are coed. However, Amherst and UMass have their own geology programs, so they wouldn’t typically need to cross-register at Smith or Holyoke. Hampshire doesn’t have much for geology, but Hampshire students would be more likely to cross-register at Amherst or UMass, because they are closer. The bottom line is that geology classes at Smith or Holyoke, unlike those at Bryn Mawr, would probably have few or no guys.