What are subsurface intrusions?

Subsurface intrusions are like hidden guests that come up from deep inside the Earth and change what’s around them.

Imagine you're playing in your sandbox, and suddenly a big, squishy blob of sand pops up right next to you, not because you dug it out, but because something came up from underneath. That's kind of how subsurface intrusions work. They’re molten rock, like lava, that moves upward from deep inside the Earth and pushes its way into the rocks above.

Sometimes these blobs of molten rock cool down slowly underground and form big, smooth shapes called batholiths, think of them as giant candy canes hidden beneath your feet. Other times, they might come up closer to the surface and create interesting features like dikes, which are like long, thin walls made of rock that cut through other rocks.

Even though you might not see them, these subsurface intrusions shape the land around us. They can make mountains bigger or even help form new kinds of rock, just like how a big blob in your sandbox could change the whole look of your play area!