A group of students measured the average pebble size at five sites along a beach transect from the sea to the cliff foot. Their results are shown in this table:
| Location | Distance from low-water mark (m) | Average pebble size (long axis in mm) |
|---|---|---|
| 1 | 5 | 12 |
| 2 | 15 | 24 |
| 3 | 25 | 35 |
| 4 | 35 | 110 |
| 5 | 45 | 48 |
The result for Location 4 is an anomaly. Suggest one possible explanation for this anomaly.
