Short Geologist asked about male/female ratios where we work. My answer was going to be a bit long, so I'm making a whole post.
At the engineering consulting firm (where I did UST and SWPA work) I was one of 4 women "professionals" (a geologist, an engineer, a chemist, and an environmental scientist), so total for "professionals" was about 4:12; there were far more women then men in the office but the rest were drafters, secretaries, personnel manager, office manager, book keeper... As far as I know there were no women on the survey crews (those crews probably brought the total male/female back up to 50/50).
Back in grad school the ratio was close to 40:60ish, a few more males than females (students only).
Where I am now there are 9 female geologist and chemists (iirc, she actually does programming for us) and 50 male geologists, biologists, and engineers. My division is 3:4 and our building (next door to most of the Survey) is 4:9, plus one volunteer lady geologist*. When I counted up my co-workers from the phone list I was kind of surprised there were actually that few women scientists. It always seems like there are more women here but in my mind I'm probably including all the support staff (accounting, personnel,...), which is mostly female. Lots of the men work either for the OGB or on the 3rd floor where I rarely go and so usually only see all those folks at holiday luncheons.
I've noticed a difference in conference attendance. When I went to the American Association of Petroleum Geologist's meeting there were definitely more men than women but at the Geological Society of America meetings I've been to (all 2 of them) it was more even. There's a small (200 people?) symposium here every spring on coalbed methane and shale gas. When I was a student my (now) boss' wife and I would be among the very few women there. (No line at the bathrooms!) now the numbers of women are creeping up. That meeting is probably still in the 25:75 range. The field trip my boss runs for that meeting is the only time I've seen men crash the ladies bathroom (1-holers at a gas station). Not uncommon for the van drivers and I to be the only women.
At the consulting job I spent most of my time in the office writing up other's reports because the guy (an engineer, who once described a sand as "well sorted, fine to coarse grained") could help our drill crew lift augers, 70lb bags of sack-crete, etc. and all I 'could' do was describe the soil. The only time I really was uncomfortable about being a lady geologist was the job with the driller who hit on me, obnoxiously, for 3 days straight. My (then) boss and his mostly thought it was funny and were laying bets as to when I'd slug the jerk. (It's surprising he managed to get the hole straight because he spent almost all of his time looking at me - and I'm not terribly attractive in field clothes and a hardhat.)
Male/female ratios aren't something I've ever worried a whole lot about. That is partly due to the fact that I've had good role models, also, with 5 brothers it doesn't bother me to be "one of the guys". Besides, I have it so much easier than it used to be. My boss' wife (a geologist) was once denied a job because they didn't have a ladies room in the building. At that time, she had a job where she had a 10 minute walk to the closest ladies room.
*with only 2 one-holers, one non-climate controlled, for us ladies!