EXERCISE 1
a) In the Google earth image of the Texas coast (Figure 1) identify the different coastal elements, listed below. Use Figure2 and the definitions below. Mark these on the image.
1. Shoreline
2. Coastline
3. Dunes
4. Bay
5. Swamp
6. Tidal marsh
7. Label the coast, backshore, foreshore, nearshore, and offshore areas
Figure 1. Google Earth image (2018) showing the Texas coast for exercise 1.
Figure 2. Coastal elements and facies.
BACKDUNE
COAST
It is the strip of land that extends from the coastline landward to the first major change in the terrain features, which are not influenced by the coastal processes.
It is the dune area behind the foredunes, after the trough. The backdune is usually forested and provides shade to its inhabitants. The backdune provides cool temperatures and moist soil adequate for many plants and animals.
BACKSHORE
Zone that is dry under normal conditions, it is characterized by present of berms and it has no vegetation. The backshore is only exposed to waves under extreme events with high tide and storm surge.
BERM
Terrace of a beach that has formed in the backshore, above the water level at high tide. Berms are commonly found on beaches that have fairly coarse sand and are the result of the deposition of material by low-energy waves.
DUNE Ridges of loose, wind-blown sand (fine to medium) forming on the backshore.
FOREDUNE
NEARSHORE
Extents seaward from the low water line beyond the breaker zone; it defines the area influenced by the nearshore currents.
It is the dune area directly behind the beach. The sand dunes are usually covered by grass, that help stabilize the sand.
INTERDUNE
It is the depressed area between the foredune and the backdune. The trough often fills with groundwater causing interdunal ponds where many organisms survive in this more stable habitat.
OFFSHORE Extents seaward from the nearshore zone.
SHORELINE
The line that marks the contact between land and sea. It migrates up and sown as the tide rises and falls.
COASTLINE
The coast’s seaward edge. The landward limit of the effect of the highest storm waves on the shore.
TIDAL MARSH
It is a type of wet land regularly inundated by the tidal action. It is located in the back part of the barrier Island.
SWAMP
It is a type of wetland characterized by low, generally saturated land covered intermittently or permanently with shallow bodies of water. It can be covered by either aquatic vegetation or vegetation that tolerates periodical inundation. The water of a swamp may be fresh water or salt water.
STOP 1. BRAZOS RIVER
After watching the video with Dr. Wellner discussing the Brazos River, you should be able to answer the following questions.
EXERCISE 2
a) Using the picture below (Figure 3), draw and describe the sedimentary structures present in the trench, what mechanisms could create these sedimentary structures.
b) In which part of the river could this structures form? Hint: use Figure 4.
Figure 3. Photo of a trench in The Brazos river.
Figure 4. Typical Bar river section. showing sedimentary structures present at each interval.
EXERCISE 3
a) The purpose of this exercise is to locate the NOAA water level station in google maps and get water levels. Follow the steps below:
1. In the link below look for the LAT and Lon of the Brazos River near Rosharon station.
LAT: . LON: _.
2. Check water levels for the Brazos River near Rosharon station in the link below, take a print screen and report today’s water level:
Date: Time: Water level (ft): .
STOP 2 & 3. MODERN AND PALEO BRAZOS RIVER DELTA
EXERCISE 4. THE FORMATION AND EROSION OF RIVER DELTAS: THE PALEO AND MODERN BRAZOS DELTA
a) Using the images below, describe the evolution of the old and the new Brazos river de
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