Brittle–ductile transition zone

Imagine you're playing with two different types of Play-Doh: one is super soft and stretchy, while the other is harder and more breakable. If you try to stretch the harder Play-Doh too far, it will eventually snap and break, while the softer one will keep stretching without breaking.

A similar thing happens with rocks under stress. Depending on various factors such as temperature and pressure, rocks can either be like the soft Play-Doh or the hard Play-Doh. In the brittle zone, rocks are like the hard Play-Doh: if too much stress is applied too quickly, they will break and fracture.

However, if the rocks are in the ductile zone, they're more like the soft Play-Doh: they can handle more stress and deformation before breaking or fracturing. The zone where rocks transition from brittle to ductile is called the brittle-ductile transition zone.

So basically, it's like the difference between trying to stretch a piece of silly putty vs. trying to stretch a piece of dry clay. The silly putty will stretch and deform without breaking, while the dry clay will eventually snap or crack. The same concept applies to rocks and their ability to handle stress and deformation.