Whether you are doing research for an assignment, or just stumble across something in your own reading, there's always a question you should consider: Is this a good source?
Below are three geography/geology articles. Look at each of them, and consider if they are good sources, and what makes them a good or bad source.
Once you have had a look at all 3, answer the poll, then move onto the next blue tab on the left, "Evaluating Sources".