Sandpile

Near-synonym: sandhill

Are there more grains of sand in a sandpile than there are atoms in a single grain of sand? This is not a precisely formulated problem, because the size of a sandpile is not well defined. The size of a grain of sand is also somewhat uncertain. Geologists usually call rock particles “sand” when the grain diameter is 0.06–2 mm (table 1.8). A crude calculation shows that a sandpile with as many grains as there are atoms in a typical single grain is very big indeed.¹⁶ Its volume is about 10¹⁰ m³, corresponding to a cube with sides longer than 1 km (0.6 mile). The problem thus has a definite answer, in spite of its imprecise nature.