Geological Chronicle
Lamont is a system of low ridges in the surface of Mare Tranquillitatis, located southeast of the crater Arago. Rising only a few hundred meters in height, the formation is considered most likely a submerged impact crater. The feature was named after Scottish-born German astronomer Johann von Lamont.
The structure forms two roughly concentric but incomplete rings with an inner diameter of 60 km and an outer diameter of 120 km. Radial ridges radiate away from the center of Lamont, except in the east and west quadrants. The ridges average 5 km in width and are thicker to the southeast. The system is readily visible only under low angles of illumination, when shadows highlight the terrain features.
The feature is associated with a mass concentration, or mascon, which marks a subsurface region of higher-density material.