Why are beaches sandy or pebbly? It’s simple, really. It just depends on the kinds of beaches they are. Cliff areas tend to have higher stronger waves, so have more pebbles. And sandy beaches tend to be areas with gentle waves. The colour depends on the content (for instance, iron oxide makes sand brown, but abroad coral quartz makes Caribbean sand white or pink – you can even find green sand).
Check tide times and avoid sinking mud. Never take pebbles from beaches (illegal in Italy) as it disturbs ecosystems. Keep dogs away from seaweed fronds (they expand in the stomach as they dry). Leave creatures (crabs etc) alone in rock pools, as many are injured, once returned to sea. Wear rubber wellies (not flops) near wet rocks or slippery seaweed.
Even dead jellyfish can sting curious dogs, and lion’s mane jellyfish and Portuguese Man O’War can be very dangerous. For stings, rinse with sea water, remove tentacles/barbs and seek immediate vet advice.