Download Exploring Ponds and Lake

Exploring Ponds and Lake
Ponds and Lakes form when water
collects in hollows and low-lying
areas of land.
Ponds
Smaller than lakes
Shallow enough for
sunlight to reach
bottom.
Plants/Algae grow
throughout.
Bottom is covered in
mud, weeds, and
algae.
Lakes
Bigger and Deeper than ponds.
Sunlight doesn’t reach bottom.
Plants only near shoreline.
Few organisms live near bottom.
Bottom is made of sand, pebbles, and rock.
5 Ways Lakes Are Formed
When river channel
loops around. (Oxbow
Lake)
Depressions created
by ice sheets that
melted in last “Ice
Age”
Created by movements
in Earth’s crust.
When water collects
inside the crater of an
inactive volcano.
Created by PEOPLE
when we build a dam
across a river. (Lake
Lure)
Why do we build lakes?
Irrigation for farming
Recreation
Drinking Water

Reservoir: a lake that stores water for drinking.
How do lakes change?
In addition to seasonal changes, a
lake can undergo long-term changes
that may eventually lead to its death.
Seasonal Changes (Lake Turnover)
In summer, sun warms the water. This warm
water floats on top of the more dense cooler
water.
In fall as the water cools, it sinks and mixes
with the water below. “Turnover.”
Lake “turnover” refreshes the supply of
nutrients throughout the lake.
Long Term Changes
Over time, nutrients build up in a process
called EUTROPHICATION.
During this process, a lake or pond will
eventually become a grassy meadow.
To determine the rate of Eutrophication, you
measure the amount of dissolved oxygen in
the water.
Eutrophication