Geoscientists include geologists, geochemists and geophysicists who conduct programs of exploration and research to extend knowledge of the structure, composition and processes of the earth, to locate, identify and extract hydrocarbon, mineral and groundwater resources and to assess and mitigate the effects of development and waste disposal projects on the environment. Oceanographers conduct programs of exploration and research on ocean processes and phenomena, biological, chemical and physical characteristics of oceans, interactions with atmospheric and geological environments and impacts of human activity on oceans and marine ecosystems. Geoscientists are employed by petroleum and mining companies, consulting geology, geophysics and engineering firms and by governments and educational institutions, or they may be self-employed. Oceanographers are employed by governments, educational institutions and private companies engaged in exploration of seafloor deposits and seafarming areas, or they may be self-employed.