Geological Chronicle
Lacus Veris (Latin for "Lake of Spring") is a crescent-shaped lunar mare centered at 16.5° S, 86.1° W. Extending roughly 396 kilometers along an irregular 90-degree arc from east to north centered on Mare Orientale, the mare covers an area of about 12,000 square kilometers between the ring-shaped Inner and Outer Rook mountains. It lies in a topographic lowland about 1 kilometer below the surrounding peaks.
Crater impact density indicates that the mare is an estimated 3.5 billion years old, finishing its formation roughly 340 million years after the impact that created the Orientale basin. Data from Lunar Orbiter missions and Earth-based telescopes show that the mare includes material from the surrounding highlands.
The mare contains eleven sinuous rilles formed from lava tubes and channels, with lengths ranging from 4 to 51 kilometers, alongside several shield volcano formations under 10 kilometers in diameter. Many of these rilles begin in the Rook mountains and flow to the base of the mountainous scarp. The geological formations and lack of collapse depressions suggest the mare was formed by thin lava flows through tubes rather than basalt flooding from fissure eruptions. Author Eric Burgess proposed the mare as a site for a future crewed lunar base, citing a 1989 study by the NASA Johnson Space Center.