sentence: Many beaches are made of sand, but some beaches are made of gravel.
sentences_before: A 'beach' is an area of lakeshore or seashore which is fairly open, slopes smoothly to the water, and is free of trees, large boulders, or anything else which might make walking difficult or impossible.
sentences_after: Beaches are easy natural landing and launching places for boats, including landing craft specially made for beaches.
concept_name: beach
headings: Beach