Angela Leigh Bolejack, age 12, of Winston Salem, North Carolina, for her question:

What is the treacherous substance in quicksand?

Swamps and marshes, bogs and quicksands are made of mixed ingredients. We cannot point to any one ingredient and say that it is the treacherous one. The treachery is in the mixture. Bogs and marshes are soupy mixtures of silt or clammy clay and water. If we separate the water, we could swim in it safely. If we separate the silt and clay, it would be solid ground, safe to walk on. But together, the mixture is to thick for swimming and too soupy to support a person's weight.

Quicksands are mixtures of water and either beach or river sand. Neither ingredient is treacherous by itself. But a person who steps in the mixture sinks down because swimming or walking is impossible. Most bogs and quicksands look like safe and solid ground. When exploring new territory, a sensible person takes care to test the ground ahead. A careless person may step into one of these treacherous traps unawares    and that first step could be disastrous.