compaction

Everyday

1. Pressing something together so it becomes tighter and smaller, with less space inside it. tree →
2. (science) The squeezing of layers of sediment or soil by weight on top, which helps turn sediment into sedimentary rock. tree →

In the lessons

In science lessons on rocks, compaction and cementation turn layers of mud and sand into sedimentary rock over millions of years. In gardening and farming, soil compaction from heavy machines or feet makes it hard for roots and water to get in. Rubbish trucks use compaction to squeeze rubbish. It tells the reader things are being pressed tighter.

Examples

• Compaction squeezes layers of sand into sandstone. tree →
• Heavy tractors cause soil compaction. tree →
• Rubbish lorries use compaction to fit more rubbish in. tree →
• We modelled compaction by pressing layers of clay together. tree →
• Roots struggle to grow in soil with too much compaction. tree →
• Road builders use rollers for compaction of gravel. tree →

Note

Uncountable. Verb: «compact» (to press tight). Not to be confused with «compact» as an adjective (small and neat) or a noun (a small make-up case, or an agreement).