The Mare Tyrrhenum quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. This quadrangle is also referred to as MC-22. It contains parts of the regions Tyrrhena Terra, Hesperia Planum, and Terra Cimmeria.

Linear ridge networks are found in various places on Mars in and around craters. These features have also been called "polygonal ridge networks", "boxwork ridges", and "reticulate ridges". Ridges often appear as mostly straight segments that intersect in a lattice-like manner. They are hundreds of meters long, tens of meters high, and several meters wide. It is thought that impacts created fractures in the surface, these fractures later acted as channels for fluids. Fluids cemented the structures. With the passage of time, surrounding material was eroded away, thereby leaving hard ridges behind. It is reasonable to think that on Mars impacts broke the ground with cracks since faults are often formed in impact craters on Earth. One could guess that these ridge networks were dikes, but dikes would go more or less in the same direction, as compared to these ridges that have a large variety of orientations. Since the ridges occur in locations with clay, these formations could serve as a marker for clay which requires water for its formation. Water here could have supported past life in these locations. Clay may also preserve fossils or other traces of past life.