This paper addresses the concept of geological time as used by students who face tasks that demand three types of skills: to locate events in time, to order them according to time calendar, and to manage time intervals. The empirical study consisted of asking high school students as well as technical school students to carry out tasks that required the use of the three previously mentioned components. It was found, first, that students frequently used erroneous temporal labels, which shows a lack of knowledge that would allow them to locate events within the context of geobiologic data. Second, the students did not store the representation of a succession of events, but were nevertheless able to create it by means of the deductive use of previous knowledge. Finally, the importance of having an appropriate representation of geological time intervals became patent while observing the students' difficulties in understanding geologic changes.
