Estuaries

Start with a mind map

Several maps on this page are titled Estuaries. Begin with a map that follows freshwater from land to the ocean through rivers, streams, groundwater and valleys. Its branches give you a way to trace the route between land and salty ocean water. Other maps present similar ideas, so compare their branches to see how the information is organized.

One map also refers to the range from stream-cut channels to broad lagoons. Use those terms alongside the flow of freshwater as you study the page.

Move on to the notes

After the maps, read the note on inverse and positive estuaries. It describes inverse estuaries as having higher salinity than the sea to which they are connected. The separate note on positive estuaries describes fjords as drowned river valleys cut by glaciers, with steep sides and deep water.

Keep the notes beside a map as you study. The map helps organize the route of freshwater, while the notes add descriptions of particular estuaries.

Check your understanding

There are no quizzes listed on this page. Instead, turn a map branch or a detail from a note into a question. For example, ask how freshwater reaches the ocean, or how the salinity of an inverse estuary compares with that of the connected sea. Then check your answer against the resource.

You can also use the note on positive estuaries to check what it says about the shape and formation of fjords.

Place the topic in the unit

Estuaries is a section of the Coasts unit in Geology and earth sciences. The maps and notes offer different starting points within this section: freshwater routes, salinity and the description of fjords. Use the Coasts unit as the context for returning to these resources as you study.

Choose a map or note and work through it at your own pace.