As the summer season winds down, you might be thinking about getting in those last trips to the beach. When you go, take a fresh look at the sandcastles your fellow beachgoers have constructed. Are some of them washed out lumps of wet sand at the waters edge? Are some dried out piles of sand slowly blowing away in the wind? Do some of them have beautifully smooth surfaces and sharp edges?

You probably figured out as a young child as I did that building sandcastles requires sand that’s wet but not too wet. But have you thought about why it is that any amount of water can turn sand into the stuff of miniature turrets, parapets and castle gates?

Colorado State University geotechnical engineer Joseph Scalia explains the fascinating science that allows sand and water to become the moldable medium beachside builders have relied on for centuries.

Also today:

Eric Smalley

Science + Technology Editor

There’s a lot of science behind the natural forces that let this guy work his magic at the beach. Victoria Pickering/Flickr

Sandcastle engineering – a geotechnical engineer explains how water, air and sand create solid structures

Joseph Scalia, Colorado State University

From capillary forces to sand grain shape, the simple mix of sand and water hides the of complexity within.

Politics + Society

Environment + Energy


Ethics + Religion

Health + Medicine

Economy + Business

From our international editions

The Conversation Quiz 🧠