In this situation you are addressing a person/group that is (relatively) familiar with the content you are going to present. In general, they will have an excellent understanding of scientific research in the Earth Sciences and potentially even in the specific field you are working in. You can therefore keep the introduction short. Results and discussion can be more extensive. If necessary you could briefly address the pros and cons of your methods, or how the results are dependent on the methods (e.g. some flaws in the data are due to the methodology; it is very common in Earth Sciences to highlight and discuss flaws in methodology/results). Try to fill your discussion section with questions and interpret your results, further discussion will happen during the questions.

In a lecture you are presenting with the purpose of teaching. Here the focus will be on bringing across information rather than the process of a specific research. Use as many schematic figures as possible to explain mechanisms. Since you are teaching your audience, it is even more important to see if the audience is following your narrative. Introduce the general topic and progress through your content gradually. Plan a break in your lecture in advance.

Conferences have a very large number of talks and lectures, so try to keep your presentation accessible. Try to get one message across very well, since after a long day of talks it is difficult to remember many details. Therefore, try to stick to one research question, and lead up to it with clear, straightforward arguments with only the data and analysis techniques you absolutely need. This will also help you shorten the presentation enough for a conference talk. After your presentation you can always elaborate (during questions or a personal conversation) if someone wants to know more.

A tip is to mention how your talk connects to the presentations before or after you. This showcases competence and vision on the topic, and it emphasizes the link between your core message and the broader theme the audience came to participate in. Of course, this only works if your talks are related to the same research area.

The overlap of prior general knowledge between you and your peers will be very large, however you will have more specific knowledge of your specific research topic. This might result in a much smaller introduction or elaborate definitions of specific jargon. Focus mainly on topic-specific processes. It may be possible to compare new mechanisms to everyday examples, and provide useful analogies for complicated concepts. Do not hesitate to mention when there is something you do not know. Try to discuss your results and pose explanations for them, but remember to make a clear distinction between research-based theories and your own hypothetical reasoning.

Science communication is a field in and of itself, so it is particularly important to prepare and practice. In this case you cannot assume that your audience has a broad background knowledge in Earth Sciences. Even more so, they will not be familiar with the specific jargon we use in this field. Everyday examples or analogies can help to make your content more accessible. Make sure you are taking your time, introducing concepts fully before moving on. Someone outside of geosciences most likely will not see the connection between the geological processes that seem straightforward to you. Keep concepts separated, and engage your audience by explaining the connections.