What made them unique was their monumental scale. 其特点是规模极大

317. was working its way to the surface.
     正朝着地表前进
318. Once these Permian eruptions started...
     二叠纪的喷发一旦开始
319. there was no stopping them.
     就无法停止
320. What made them unique was their monumental scale.
     其特点是规模极大
321. They were among the largest,
     是生命见证过的
322. most violent eruptions that life has ever witnessed.
     最大、最猛烈的喷发之一
323. And they raged for 100,000 years.
     持续肆虐了10万年

来自《我们星球上的生命 第一季 第三集 Life on Our Planet S01E03 入侵大地》第 320 行