Tag Archives: concrete

(and other secrets from the world’s oldest man-made material) The world’s oldest man-made material is probably more familiar than you’d think. Although humans invented this technological marvel about 12,000 years ago, we still use it today!  Concrete is everywhere! It paves our sidewalks, supports our skyscrapers, and dams our rivers. It might be the mostContinue reading “How tiny sea creatures built an ancient city”