West-east-trending valleys score the Phlegra Montes region with a strike that is coincident with the orientation of graben to the west of the mountains, suggesting that regional extensional tectonism affected this region of Mars. Graben along this trend are also present in Galaxias Chaos and into Utopia Planitia. In the Phlegra Montes, some of these graben have been interpreted to host glaciers that have since given way to flow-like landforms called lineated valley fills (LVF). This is not considered a typical way for such landforms to occur on Mars. It has been proposed that the tectonic environment of these valleys was directly controlled by volcanism from the Elysium Rise. The Phlegra Dorsa, a fleet of north-south-trending wrinkle ridges, run largely parallel to the massifs of the Phlegra Montes. These ridges have been morphologically likened by some researchers to sinuous ridges found on lunar maria; they are typically distributed where volcanic flows from the Elysium Rise meet with the older terrains comprising the Phlegra Montes region. Some researchers have found that the formation of these wrinkle ridges has best fit a modeled global stress field involving contributions from the Tharsis Rise, Elysium, and Hecates Tholus (thought to precede Elysium Mons).