The view from Google Earth: Water

Google Earth does not take pictures of the oceans. But the rivers, lakes and coasts are fascinating enough.

Here are the meanders in a small tributary of the Amazon. Meanders are characteristic of rivers which are leisurely flowing through a floodplain and depositing sediment along the way.

Here are meanders in lake Powell in Arizona, US. After the Glen Canyon dam was built, the Colorado river backed up and filled up these meanders which will remain static and unchanging.

Here is Majuli: a river island in Brahmaputra river in India --very close to my hometown Jorhat. Note the extensive braiding pattern on the river. Before entering Assam, the Brahmaputra flows through a very steep canyon and hence carries an extensive load of sediment. This sediment is deposited on the floodplains of Assam and the sediment causes the river to subdivide into many streams which fork and rejoin leaving small islands in the middle.
The sediment deposited by the Brahmaputra is a mix of grayish-white sand mixed with a lot of organic matter. This is very different from most other rivers in Assam which deposit typical coarse brown sand. I have no idea why the colors of should differ so much.


This is the Brahmaputra river delta in Bangladesh: Sundarban. Again notice the extensive braiding of the river channels caused by deposition of sediment before the river runs into the sea to the Bay of Bengal. The Sundarbans are known for extensive magrove forests.



This is Redwood Shores lagoon on San Francisco bay. The brown stream empties into the San Francisco Bay. The unusual color of the water is caused by halophilic (salt-loving) bacteria. The stream presents a hierarchical branching pattern of drainage which is typically seen in much larger scale in large river systems.

The two pictures above are from the Lena river delta. In the top picture, braiding is obvious. In the bottom picture you can see lakes in the delta with frozen boundaries.

The San Francisco bay salt marshes are an endless source of strange colors and forms.

The view from Google Earth: Deserts

I find deserts fascinating.

This is a dry riverbed in Sahara in northern Algeria. Desert streams flow only intermittently when a rare storm hits the desert. Since the desert is bereft of any vegetation, storm water flows downslope violently and can cause deep erosion in a matter of hours. The result is a beautiful fractal-like pattern of drainage. A very similar dendritic pattern can be seen in growing trees or crystals which are formed not by erosion, but by growth.

Although deserts get little rain, erosion and lack of tree cover makes them ideal for observing water based erosion. These two pictures show watercourse patterns in Sahara. The top picture is from Chad in the Tibesti mountains while the bottom one shows a picture from Ahaggar mountains (Algeria).

This is a pair of start shaped dunes in eastern Algeria. Typical dunes are crescent shaped and they form transverse to prevailing winds. If the prevailing winds are multi-directional, then we begin to see star shaped dunes instead.

These are dunes in Rub-al-Khali (The Empty Quarter) in Saudi Arabia. The dunes are formed orthogonal to the prevailing wind directions.

These dunes are near Sossus Vlei in Namib-Naukluft national park in Namibia. The Namib desert is a temperate desert and has some of the tallest and reddest dunes among all deserts. The red coloration comes from oxidized iron compounds. Sossus Vlei is the remnant of a lake which has dried up and left behind a salty flat. Next to Sossus Vlei is Dead Vlei which is a spectacular photography location.

Twisted land forms in southern Algeria. My speculation is that this is an ancient lake bed with a dry salt pan at the center.