Seminars on geology will focus on the four main points of study of the Earth itself. These are the materials the Earth is made of, the structure presented in those materials, the effects of outside influences on those structures and how the entirety changes over time. Explain the main materials of the earth, focusing on oil, water, rocks and metals. Talk about the Earth processes affecting each one, like floods, volcanoes, landslides and earthquakes. Take into account the history of geology, including topics like climate change.
Seminars on mineral sciences will go through how minerals distribute chemicals and nutrients throughout the Earth's soil, helping define the Earth's crust. Specific seminars can focus on certain minerals and their impurities, basing the talks on what makes up each mineral and what specifically causes such defects. The study of minerals includes the study of gemstones, so a talk could deal specifically with discovery and grading of gemstones.
Seminars on geochemistry apply specifically to the chemistry of the Earth. They would cover the processes and reactions that dictate rock composition. This differs from petrology, which deals with a more biological and physical aspect of rock formation. Go over the classifications of rocks based on their chemical makeup, including: acid rocks, basic rocks, intermediate rocks and mafic rocks. Explain the proportions of each chemical necessary for this classification.
Seminars on petrology, or the study of rocks, can be an overview of the history of the Earth as told through its many ores and minerals from core to crust. Explain how you can tell time by looking at density and width of each rock layer in any given section of earth and dig deeper by showing what elements students will be looking for to describe what happened during any specific segment. It's evolution through rock bed.