Macrostrat is a great tool for anyone doing research in geology. Macrostrat is a site where geologic data related to "the spatial and temporal distribution of sedimentary, igneous, and metamorphic rocks" (Macrostrat - About) is gathered. The database is searchable and links to xDD, a site that authenticates, indexes, and allows searching of scholarly publications (xDD - About)
What does xDD stand for? Originally called GeoDeepDive, this site was renamed to reflect its mission beyond geology. The new name, xDD stands for Extraction of Dark Data. It serves as a central hub that gathers scholarly works and where they can be searched all at once.
xDD is a site that is maintained by the University of Wisconsin through funding from the National Science Foundation (NSF), and the Defense Advanced Research Projects Agency (DARPA). This work is also supported through partnerships with several professional societies, publishers, and governmental agencies.
To get started, click on the 
button in the center of the page. This will open an image of the earth with all political boundaries marked and the geologic information color-coded.
Next, choose the area that you want to study. To move around the earth you can use your mouse and click and drag to rotate the earth or you can use the arrows on your keyboard to rotate the earth. You may need to click on the earth before it will rotate using the keyboard.
Once you have located the area, you need to zoom in. You can do this by using a scroll wheel on the mouse or the plus (+) or minus (-) keys.
Click on the geologic formation that you are interested in to see what data Macrostrat has. Many areas have a section of information called, "Primary Literature". This section includes publications on a wide variety of topics; including water resources, historical biology, paleogeography, and sedimentary research. Most publications have links that will take you directly to the published paper.