A very common error is the inappropriate use of the future tense. Because they are universal, laws and general principles or situations are described in the present tense. For every action, there is an equal but opposite reaction. If a river overflows its banks, the land nearby floods. When underflow is the only mechanism of transport, sediment is distributed more evenly throughout the lake. Use the future tense only to refer to events that are uniquely in the future. Scientists predict that storms will be more severe as a result of global warming. Logic dictates that other parts of the document that you are writing are referred to in the present tense, regardless of whether they precede or follow. Sedimentary structures are described in Chapter 3 (not will be). Our paper explains the results of three experiments. The reader may read about these in the future but the descriptions or explanations are there already. In discussing your findings, use the past tense to refer to things or events that were. We measured four stones. The experiment ran for six days. Use the present tense for those that still are. Sediment overlies bedrock in three places. Our results show ... Use the past tense to refer to the actions of other writers. Jones (1991) reported that ... Use the present tense to refer to publications or their contents. The paper by Jones (1991) contains information on ... Results presented by Jones (1991) show ... Jones did; her paper and results still do.