Volcanic activity of the McMurdo Volcanic Group is tied to continental rifting and commenced during the Oligocene. The West Antarctic Rift is one of the largest continental rifts on Earth but little known and possibly inactive today. The Ross Sea and the Victoria Land Basin developed along this rift and were deeply buried, while the Transantarctic Mountains were rapidly uplifted during the last 50 million years and are located on the shoulder of the rift. The line separating the two is a major crustal suture, with large differences in elevation and crustal thickness across the suture. Many of the volcanoes appear to have formed under the influence of fault zones in the area and increased activity in the last 30 million years has been correlated to the reactivation of faults.