Accretion - Gradual addition of new land to old by deposit of sediment carried by water.

Alluvial - A deposit of clay, silt, sand, and gravel left by flowing streams in a river valley or delta, typically producing fertile soil

Alpine - A plant native to mountain districts, often suitable for growing in rock gardens
- Of or relating to high mountains

Apex - The top or highest part of something, esp. one forming a point

Avulsion - The sudden separation of land from one property and its attachment to another, esp. by flooding or a change in the course of a river.

Benthal - of or relating to or happening on the bottom under a body of water.

Caldera - A large volcanic crater, typically one formed by a major eruption leading to the collapse of the mouth of the volcano.

Cataract - A large waterfall.
- A sudden rush of water; a downpour.

Confluence - The junction of two rivers, esp. rivers of approximately equal width.

Eddy -
Verb: (of water, air, or smoke) Move in a circular way.
Noun: A movement of water, counter to a main current, causing a small whirlpool.

Estuary - The tidal mouth of a river, where the tide meets the stream.

Meridian - A circle of constant longitude passing through a given place on the earth's surface and the terrestrial poles.

Sedimentary - Related to Matter that settles to the bottom of a liquid; dregs.

Tundra - A vast, flat, treeless Arctic region of Europe, Asia, and North America in which the subsoil is permanently frozen.