在地质和行星科学（GPS）部门，教师和学生研究地球和其他行星，以便了解它们的起源，组成和发展。地球化学是对地球及其组成部分的化学和结构组成及其演化的研究。包括大气，水圈，地壳，地幔和核心等部分，以及诸如陨石和彗星，其他行星，太阳和遥远的恒星等地外物质。它涉及地球及其大气中元素的分布和迁移。随着时间的流逝，地球化学已经从描述性科学演变为越来越关注其观测结果背后的机理的地球化学。如今，地球化学已细分为许多子领域，包括水成地球化学，宇宙化学，无机地球化学，同位素地球化学，有机地球化学和微量元素地球化学。由于大多
The Geological and Planetary Science (GPS) major is designed to provide its students with a thorough training in the geological and planetary sciences and, whenever possible, to integrate these studies with the core curriculum courses in mathematics, physics, chemistry, and biology that all students take during their first years at Caltech. Students may elect to pursue a specialization track under the GPS major, which include geology, geobiology, geochemistry, geophysics, and planetary science.