Sea gravel

… Gravel is called different names depending on where it is deposited as a group. If it is deposited in the sea, it is called sea gravel; if it is deposited in a river, it is called river gravel (or river gravel); if it is deposited in an old river, i.e., in the area around a current river that has already been flattened (old riverbed), it is called land gravel; if the area where it is deposited has been left behind by uplift or erosion and has become mountainous or terraced, it is called mountain gravel. Compared to other types of gravel, river gravel is the closest to being spherical, and there are more of smaller grain sizes in the downstream area than in the upstream area. …

*Some of the terminology that refers to "sea gravel" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…　砂利は，その集合体として堆積している場所によって呼名が変わる。堆積場所が海であれば海砂利，河川であれば川砂利(または河川砂利)，旧河川すなわち現在の河川の周辺で，すでに平地化した部分(旧河川敷)であれば陸（おか）砂利，堆積地が隆起または浸食によって取り残され，山地状または段丘となった部分のものを山砂利という。川砂利は他の砂利にくらべると最も球形に近く，上流域よりも下流域のほうが粒径の小さいものが多い。…

※「海砂利」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報