This study aims to probe into the interest on earth science of the science teachers with science knowledge and the relationship between their consideration on the frequency of the said subject used in teaching and their cognition of geological time. This study is based on questionnaire survey and selects 111 science teachers with science knowledge in elementary schools by purposive sampling. The research finding demonstrates that the teachers are interested in these 20 earth science topics with at least medium level; however, the frequencies of these topics used are varied (from medium to low levels). The earth science topics which the teachers are interested in the most tend to be taught frequently whereas those which they are not interested in are rarely taught; the teachers have low level of cognition on geological time. Finally, this study elaborates the research topic and proposes suggestions with regard to teacher education and research approaches.