Science Section 7.2 Study Set

What makes up a stream system?

All the streams that drain water from one area of land

Delta

An area of land at the end, or mouth, of a river that is formed by the buildup of sediment.

Drainage basin

An area of land in which water drains into a stream system. The borders of a drainage basin are called divides.

Sinkhole

An open basin that forms when the roof of a cavern becomes so thin that it falls in.

How do streams change as they flow from mountains down to plains?

As streams flow toward flat plains, they are in valleys that are V-shape. Streams then become less steep and then wider and curvier.

What area of land floods when a stream overflows its banks?

Floodplain

Why is fertile land often found on flat land around rivers?

Floods deposit a lot of sediment onto the floodplain, which makes that land good for growing crops.

Why do caverns form in areas with limestone?

Limestone is a rock that is dissolved by acid in rainwater.

What do you call curves and bends in a stream?

Meanders

Why can underground water dissolve limestone?

Rainwater is acidic

How do caverns form?

Rainwater that is slightly acidic dissolves limestone underground creating caverns.

Why does an alluvial fan form where a stream enters a much flatter area?

The stream slows down and deposits much of its sediment.

What is the name of the highest level of water underground?

Water table

Divide

A continuous high line of land or ridge from which water drains to one side or the other.

What do you call the area drained by a stream system?

A drainage basin

What is the difference between a drainage basin and a divide?

A drainage basin is an area into which water flows from a divide. A divide forms a border of drainage basins.

Alluvial Fan

A fan-shaped deposit of sediment at the base of a slope, formed as water flows down the slope and spreads at the bottom.

Floodplain

A flat area of land on either side of a stream that becomes flooded when a river overflows its banks.