Friday, March 2, 2018

Big Bend National Park ~~ Boquillas Canyon & Chisos Mountains

Our first stop in Big Bend was at Panther Junction Visitor Center, which is the park's headquarters and the major visitor center with lots of exhibits and a film about the park. The film was great, narrated by Peter Coyote, telling about the park and how it came to exist. Big Bend lies in the northern part of the Chihuahuan Desert, one of North America's four major deserts. It also hosts the Chisos Mountains, which is the only mountain range to exist solely within a national park.  

The Chihuahuan Desert, along with the Great Basin, Mojave, and Sonoran Deserts are found in North America.

In the Sonoran Desert (southwestern Arizona, southeastern California, Baja California, Sonora, Mexico), rains occur in summer and winter.

The Great Basin (Oregon, California, Nevada, Idaho, and Utah) is a "cold desert." It receives most of its moisture from snowfall.

Duck Billed Dinosaur
The bone you see below is from a Duck Billed Dinosaur, which was discovered at Big Bend. This dinosaur lived about 75 million years ago. It is estimated to have been about 10 feet tall at the hip, was 20 to over 30 feet in length, and weighed 2-3 tons. It is called "duck billed" for its wide jaws, which were adapted for grazing on ground vegetation.

Thigh bone from a Duck Billed Dinosaur
Where the Dinosaurs roamed. Over a dozen species, including species previously unknown to science, have been discovered at Big Bend National Park. In addition, numerous fossils of plants, fish, frogs, salamanders, turtles, crocodiles, lizards and early mammals have been found. These discoveries provide a picture of the evolving prehistoric ecosystem, allowing us to visualize life as it existed and changed tens of millions of years ago. 

The Rio Grande River runs from the Rockies to the Gulf of Mexico. Rising in the 14,000-foot peaks of Colorado's San Juan Mountains, the Rio Grande flows 1,885 miles  to sea level at the Gulf of Mexico. The river passes through three states in the Southwest, and forms the common border of Texas and Mexico for over 1,750 miles. The Rio Grande and its major Mexican tributary, the Rio Conchos, drain 185,000 square miles of mostly arid land, where demand for water is greater than supply and evaporation is greater than precipitation. Today, as in the past, the Rio Conchos is the major source of water in this reach of the Rio Grande.

Our next stop was the Boquillas Canyon Trail, which climbs and then descends to the river floodplain. I walked the 1.4 mile round trip to see the Rio Grande as it disappears into the canyon. As I approached the end of the trail, I found trinkets that a Mexican set out in hopes of getting a sale. I also encountered a "singing Mexican" who brought his boat over from Mexico in hopes of making some extra money. At the end of the trail the Rio Grande is low right now, and easily crossable. One of the main sources of income in Boquillas Del Carmen, Mexico, is the tourist industry who pay the guides to take them across the Rio Grande and up to the Mexican Immigration Department, and then shop and eat in their restaurants. They obviously do not want a wall put up here. How can one be put up? In the middle of the Rio Grande? And what would happen to the inhabitants of Boquillas Del Carmen ~~ they do not want a wall here.

Rio Grande making a 90 degree turn

Boquillas Canyon Trail

Canyon Walls

Looking up river
After leaving Boquillas Canyon, we were going to go across to Mexico at Boquillas Crossing, but we would have had to go by boat, or walk across the river, but we opted not to go. Lucy had been having intestinal distress and I was worried about leaving her for a long time in the truck. So, we went to a picnic area for lunch, then went to a boat ramp that took us down to the Rio Grande.  We took the girls with us and let them loose to run and play in the river. 

Our final stop was a drive into the Chisos Basin and the Chisos Mountain Range. The Chisos Mountains are the only mountain range to exist totally within a national park. 

The Window
The woodland around this area once extended to the banks of the Rio Grande, over 3,000 feet lower in elevation to where we were standing. Around 8,000 years ago the climate began getting warmer and drier, stranding these trees, and the animals that live among them, in the cool, moist shelter of the Chisos Mountains and other nearby ranges. These "mountain islands" separated by an ocean of desert protect small populations of woodland species, living relics of the last ice age. 

Casa Grande

Toll Mountain
Volcanic eruptions between 17 million and 38 million years ago formed the Chisos Mountains. Some of the mountain peaks may have been volcanic vents that spewed gases, rocks, ash, and lava in violent eruptions.

In other areas thick lava oozed up slowly through huge fissures and hardened into enormous rounded mounds known as lava domes. Following the volcanic activity, millions of years of erosion wore down these mountains and partially filled the basin with sediments. Now the sediments are being eroded and carried out of the Basin through the Window.

Green Gulch was once covered with forest. Lumbering turned it into a grassland, and overgrazing in the early 1940s reduced it to a desert scrub. Now protected from human interference, the canyon is becoming a mix of mountain and desert vegetation.

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