thumb|upright=1.35|Close view of pebbles
I appreciate your request, but I cannot write an accurate overview based solely on the provided context. The context consists only of an image caption ("thumb|upright=1.35|Close view of pebbles") with no substantive information about what pebbles are, their characteristics, formation, or significance. To provide an accurate 2-sentence overview, I would need to either include general knowledge or have access to a proper definition or descriptive text about pebbles, which would go beyond your instruction to base my response only on this context.
AI-generated from the Wikipedia summary — may contain errors.
thumb|upright=1.35|Close view of pebbles
A pebble is a clast of rock with a particle size of based on the Udden-Wentworth scale of sedimentology. Pebbles are generally considered larger than granules ( in diameter) and smaller than cobbles ( in diameter). A rock made predominantly of pebbles is termed a conglomerate. Pebble tools are among the earliest known man-made artifacts, dating from the Palaeolithic period of human history.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).