Any single time that the researcher goes out in the field, the chart below is a must. At least for the and Cenozoic stratigraphy of Saskatchewan as the chart shows the distribution of all identifiable formations across Saskatchewan. Being able to pinpoint where exactly you are in term of geological time will ease up the work in the field by giving you an indication about the sediments to encounter, about the sedimentary structures you should expect and ultimately about the environment of deposition at that time.
Correlation chart of Cretaceous geological units in Saskatchewan. (https://pubsaskdev.blob.core.windows.net/pubsask-prod/9496/9496-StratigraphicCorrelationChart.pdf)
The Mesozoic Era, also called the Age of Reptiles and the Age of Conifers, is the second-to-last era of Earth's geological history, lasting from about 252 to 66 million years ago and comprising the Triassic, Jurassic and Cretaceous Periods.