Tuesday, 31 May 2016


By: Luis, Nerea, Vero and Hanan 4ºB
Big Bend National Park TX, USA

•Type of ecosystem that it represents:
The vast majority of the Big Bend’s National Park ecosystem consists of desert, specifically the Chihuahuan desert, which shares boundaries with Mexico.The mountain ecosystem is also really present in the park, with its numerous, old mountain ranges formed millions of years ago that gather great biodiversity of species, as well as important geological evidence. The Chisos Mountains or the Sierra del Carmen are two examples of them. You can find as well impressive canyons, such as the Santa Elena canyon, and limestone cliffs within the Big Bend National Park in Texas. Another different type of ecosystem you can find in the park is the river ecosystem, thanks to Rio Grande or Río Bravo, which is the fifth longest river system in North America.

·Geographical location.
The Big Bend National Park is placed in Texas -the second largest state in USA. It is located in the boundary with Mexico, separated by the Rio Grande/ Río Bravo



The very complex geological history of the area makes the study of it really difficult, yet the different strata in the land are easily observed because of the scarce vegetation. There are very different kinds of rocks in the park from very distant times in its geological history. The oldest rocks of the park are estimated to be 500 million years old. Rock outcrops and sand dunes can as well be found in the park, and animal activity is also a necessary factor in the shaping of the land.                                       

-Structural factors:
Mountains were created due to several compression periods during the park’s history. Volcanic eruptions and faulting periods due to earthquakes also contributed to form its current stark, rocky and mountainous landscape. strata.jpg

-Lithological factors:
You can find sandstone and shale beds 300 million years old, formed when clay, gravel and sand layers were accumulated in a sea that invaded the area. Limestone layers were then formed, and limestone is currently one of the most predominant rocks throughout the Big Bend’s mountains, cliffs and canyons.

The erosion of higher areas of land caused the filling of the surrounding basins of the area. Calcite in rocks is dissolved by carbonic acid (H2CO3) and it is transported by rapid runoff. Acid rain is produced when oxygen from rainwater reacts with the minerals that contain sulphur. This acid rain is responsible for the erosion of limestone cliffs.
The characteristic reddish-brown colour of the landscape of the park is due to rust (iron oxide) produced in igneous rocks (formed during volcanic activity periods) rich in iron sulfide (pyrite), when water replaces the sulphur with oxygen.

Many fossils from the Cretaceous period onwards have been found in the national park, such as oysters, ammonites, crocodiles or even dinosaurs.  


Spring is warm and pleasant. Summers are hot, in the desert zones temperatures could reach 100ºF (37ºC), and in the Chisos Mountains between 80ºF-90ºF (26ºC-32ºC). May and June are the hottests months. In fall the temperature decreases and winters are mild, although there are periods of freezing cold (with light snow). There is a rainy season from mid-June to October with heavy rains and possible floods. The positive side is that the rain cools down the desert zones during the afternoons and evenings. Depending on the elevation of each zone, the air changes: temperatures in the Chisos Mountains can be 20º cooler than in the Río Grande.  


As we can see we can find really different types of animals in this National park like for example we can find from cougars to rats and to coyotes.
This is a cougar. It is also known as             
                                                                the mountain lion.              
Greater roadrunner is also known as the  
                                                         chaparral cock
black-tailed jackrabbit is also known as the
                                                      American  desert hale
kangaroo rat is named like this because they      
                                                         jump in a similar way as the kangaroo
Golden eagle it belongs to the accipitridae family
The collared peccary belongs to the Tayassuidae
Coyote, it’s closest relative is the grey wolf
American black bear it is a medium sized bear native
                                                  to north america
northern tufted flycatcher  is a small passerine bird in
                                                  the tyrant flycatcher family
mexican wolf also known as the lobo

And then we have the flora of the Big Bend National Park
Pitaya, is the fruit of several cactus species
Bluebonnets  is a name given to any number of species of
                                                       the genus Lupinus
Claret cup,  is a species of hedgehog cactus known by several
                                                  common names, including Kingcup cactus
Prickly pear it is a fruit produced by the Opuntia

Yucca  is a genus of perennial shrubs and trees in the
                                                        family Asparagaceae.

Then we have the food web that shows us which living being feeds on the other.

Resources of the biocenosis:
Wikipedia for all the animals and the plants names.
For the pictures we used google images.

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