<p>It's very common to switch majors between frosh and s'more years, and even somewhat common to switch before junior year, especially to an overlapping field, and still graduate in four years. The geology majors (geology, geobiology, geochemistry, geophysics, and planetary science) all have fairly minimal requirements that make it possible to complete everything in two years, particularly if you've done some of the more difficult courses already in another major (Ch 41, ACM 95.) Most people who graduate with a geology major are people who switched to it after their frosh year, so you would not be alone. These majors tend to get switched into because they're generally considered the easiest technical majors, the classes are pretty cool, the "labs" are field trips to awesome places (Hawaii, Alaska, Mexico, China,) and most people had little or no exposure to geology before coming to Tech. ChemE, on the other hand, has more requirements than any other major, and is probably not as much fun.</p>
<p>Most people majoring in ChemE are going to work in industry, either immediately after graduating undergrad or after getting a masters. Geology majors have some options in industry (oil, mining?) but I think a lot more go on to get a PhD in their field and go into more academic jobs (government or university research.) Also, Caltech has an excellent reputation in all of the geological sciences. Chemistry majors also go to grad school in pretty high rates, and generally work in research fields as well. Overall, a ChemE major is probably going to get the most money and have the easiest time finding a job without grad school. That said, you could probably switch from any one of these majors to many scientific/engineering fields with just a few carefully-applied years of grad school.</p>
<p>If you want to do astrobiology, geobiology or planetary science would probably be the most appropriate majors. It's not to hard to find astrobiology related SURF projects, particularly at JPL. Speleology is a very specialized subject, but any of the geology majors would probably be fine for it. It would probably be a lot harder to find research opportunities in this field.</p>
<p>If you're seriously interested in caving, this</a> group meets every month on campus. If you want to learn climbing, there are students here that are serious climbers. There's a rock climbing class that will teach you all of the basics and let you meet other Techers who are interested in climbing. Climbing and caving skills are certainly not necessary for being a geologist. The trips mostly just require you to be in good enough shape to hike a reasonable distance. However, if you get really into geology, they're probably fun in addition to being educational. </p>
<p>Some classes you might want to take your frosh year to help you pick from chem/geo majors: Ch 10, ChE 10, Ge 10, Ge 100 (seminars on current research in each field at Caltech) and Ge 1 (menu course in geology -- covers a large range of topics and two days of field trip.) If you have a particularly strong background in chemistry (not just getting a 5 on the AP test) you might want to consider passing out of Ch 1 and taking Ch 41 your freshman year. You can also take them concurrently frosh year, though this isn't done very often. It will make your life a lot easier, especially if you eventually major in ChemE.</p>