Pebbles Are Defined by Size, Not by Shape
A pebble is a small smooth stone. Geology gives it a precise size range on the standard sediment scale.
A pebble is a small stone rounded by water. Geology sizes it exactly: pebbles run from four to sixty-four millimetres, between granules below and cobbles above. The rounding comes from abrasion during transport, so a well-rounded pebble has travelled a long way, and geologists read roundness as a record of distance.
- A small rounded stone. *A beach pebble.*
- Pebbly — covered with pebbles. *A pebbly shore.*
- Pebbledash — a wall finish. *Pebbledash rendering.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | pebble | A smooth pebble. |
| Plural | pebbles | A bank of pebbles. |
| Adjective | pebbly | A pebbly beach. |
| Compound | pebbledash | Grey pebbledash. |
| Related | shingle | A shingle beach. |
How it is used in a sentence
- Pebbles are 4 to 64 millimetres.Geological definition.
- Roundness records distance travelled.Sedimentology.
- Pebbledash covers a rendered wall.British building.
The sediment size scale
- Clay — finest, under 0.004 mm
- Silt — up to 0.063 mm
- Sand — up to 2 mm
- Granule — 2 to 4 mm
- Pebble — 4 to 64 mm, then cobble and boulder
From Old English *papol-stan*, a pebble stone, of uncertain earlier origin and possibly imitative of the sound of shifting stones.
Why are pebbles round?
Abrasion during transport by water wears away the corners. The rounder a pebble, the further it has generally travelled.
Pebble or shingle?
Shingle is the British collective term for a beach of pebbles. Pebble names the individual stone.