primitive groove

例句：

1. 1. The ancient civilizations left behind many primitive grooves in their rock carvings.
   古代文明在岩石雕刻中留下了许多原始沟槽。
2. 2.The discovery of this primitive groove has led to a new understanding of the planet's geological history.
   这一原始沟槽的发现为我们理解地球地质历史提供了新的视角。
3. 3. The team spent months mapping out these primitive grooves before finally identifying the source of the water.
   团队花了数月时间对这些原始沟槽进行测绘，最终确定了水源。