Advice on Science passages

I think there are three concrete things to help with tough science passages like this one. First, I think it's important to remember that this really isn't about the science. Despite the concepts not being as familiar, the passages are all either constructing arguments about concepts or narrating a story about concepts. Whether the concepts are science, art, history, or whatever, our job is to understand what the author thinks. Second, I think it's critical to focus on the why and the what, and less about the how. That is, we need a good high level understanding of what the thing in question is, and why the author is telling us about it, but the exact mechanics are less important. Third, i think it's critical to try to visualize the things discussed when possible. For this passage I would try as hard to make a mental map when they were discussing a body of water. Finally, don't get intimidated by unfamiliar terms, as try to read more texts about science written for the popular audience. Most newspapers have a science section.