Dear friend, you have asked a very good and practical question. The geologist is a person who studies the solid and the liquid matter that constitutes the earth as well as the processes and history that have shaped it. The subject geology includes the subjects like physics, chemistry and biology as well as other sciences. Based upon the specialization of a geologist, the resume has to be prepared. For example there are many specialization in geology;
Dendrochronology
Economic geology
Engineering geology
Geophysics
Geochemistry
Geobiology
Geochronology
Geomorphology
Hydrogeology
Igneous Petrology
Metamorphic geology
Marine geology
Palaeontology
Pedology
Sedimentology
Structural geology
and Volcanology, there could be many more.

Based upon your specialization, you have to write your resume. One more important thing, you have to write your resume as per the requirement of the job. Gone are the days, when we use to prepared on resume and send that for every job opening. Now we have to emphasize the quality which has been asked by the employer or advertisement.

The resume also vary from the organization you wish to apply. In government sector (universities, colleges and research institutes) you have to pay emphasis on acdemic as well as research aspects. In private company or multinational company or some exploring company the academic experience is not that important, here your practical as well as research experience will count.

For a typical resume of a geologist, you should start with
Your name, contact address
Education qualifications
Professional experience or relevant academic experience (it may also include if you have undergone for some summer trainings to upgrade your technical skills)
Key accomplishments eg. successfully implementation of some system, or successfully exploration of some area or some type of modelling has been done. Please mention if something novel has been done. If you have some experience of new instruments, do mention that. If you have knowledge of some new or different technology or you have experience of abroad, this will give you an added advantage.
Courses under taken for teaching purposes, classes taught (graduation, post graduation or doctoral degree), Number of international, national conferences, workshops, symposium attended / participated or organized. The number of training programs attended / participated or organized. The research papers, review articles published. Number of book, book chapters published. Number of students (post graduate or doctoral degree) guided for research purpose, as supervisor or co-supervisor. This should only be mentioned if applying for an academic position.

Your resume should be brief, covering your all achievements and what you wish to do in future.

With all my best wishes

Good Luck...