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Monday, April 20, 2020

Sequoia National Park

From Wikipedia, the free encyclopedia
 
Sequoia National Park
IUCN category II (national park)
General Sherman tree looking up.jpg
The General Sherman Tree, the largest tree in the world.
Map showing the location of Sequoia National Park
Map showing the location of Sequoia National Park
Location in California
LocationTulare County, California, United States
Nearest cityVisalia, California
Coordinates36°33′53″N 118°46′24″WCoordinates: 36°33′53″N 118°46′24″W
Area404,064 acres (1,635.19 km2)
EstablishedSeptember 25, 1890
Visitors1,229,594 (in 2018)
Governing bodyNational Park Service
WebsiteOfficial website 

Sequoia National Park is an American national park in the southern Sierra Nevada east of Visalia, California. The park was established on September 25, 1890 to protect 404,064 acres (631 sq mi; 163,519 ha; 1,635 km2) of forested mountainous terrain. Encompassing a vertical relief of nearly 13,000 feet (4,000 m), the park contains the highest point in the contiguous United States, Mount Whitney, at 14,505 feet (4,421 m) above sea level. The park is south of, and contiguous with, Kings Canyon National Park; both parks are administered by the National Park Service together as the Sequoia and Kings Canyon National Parks. UNESCO designated the areas as Sequoia-Kings Canyon Biosphere Reserve in 1976.

The park is notable for its giant sequoia trees, including the General Sherman tree, the largest tree on Earth. The General Sherman tree grows in the Giant Forest, which contains five of the ten largest trees in the world. The Giant Forest is connected by the Generals Highway to Kings Canyon National Park's General Grant Grove, home of the General Grant tree among other giant sequoias. The park's giant sequoia forests are part of 202,430 acres (316 sq mi; 81,921 ha; 819 km2) of old-growth forests shared by Sequoia and Kings Canyon National Parks. The parks preserve a landscape that still resembles the southern Sierra Nevada before Euro-American settlement.

Front country

Many park visitors enter Sequoia National Park through its southern entrance near the town of Three Rivers at Ash Mountain at 1,700 ft (520 m) elevation. The lower elevations around Ash Mountain contain the only National Park Service-protected California Foothills ecosystem, consisting of blue oak woodlands, foothills chaparral, grasslands, yucca plants, and steep, mild river valleys. The region is also home to abundant wildlife: bobcats, foxes, ground squirrels, rattlesnakes, and mule deer are commonly seen in this area, and more rarely, reclusive mountain lions and the Pacific fisher are seen as well. The last California grizzly was killed in this park in 1922 (at Horse Corral Meadow). The California Black Oak is a key transition species between the chaparral and higher elevation conifer forest.

At higher elevations in the front country, between 5,500 and 9,000 feet (1,700 and 2,700 m) in elevation, the landscape becomes montane forest-dominated coniferous belt. Found here are Ponderosa, Jeffrey, sugar, and lodgepole pine trees, as well as abundant white and red fir. Found here too are the giant sequoia trees, the most massive living single-stem trees on earth. Between the trees, spring and summer snowmelts sometimes fan out to form lush, though delicate, meadows. In this region, visitors often see mule deer, Douglas squirrels, and American black bears, which sometimes break into unattended cars to eat food left by careless visitors. There are plans to reintroduce the bighorn sheep to this park.

Back country

The High Sierra Trail above Hamilton Lake passes over the Great Western Divide
 
The vast majority of the park is roadless wilderness; no road crosses the Sierra Nevada within the park's boundaries. 84 percent of Sequoia and Kings Canyon National Parks is designated wilderness and is accessible only by foot or by horseback. The majority was designated Sequoia-Kings Canyon Wilderness in 1984 and the southwest portion was protected as John Krebs Wilderness in 2009.

Sequoia's backcountry offers a vast expanse of high-alpine wonders. Covering the highest-elevation region of the High Sierra, the backcountry includes Mount Whitney on the eastern border of the park, accessible from the Giant Forest via the High Sierra Trail. On a traveler's path along this 35-mile (56 km) backcountry trail, one passes through about 10 miles (16 km) of montane forest before reaching the backcountry resort of Bearpaw Meadow, just short of the Great Western Divide.

Continuing along the High Sierra Trail over the Great Western Divide via Kaweah Gap, one passes from the Kaweah River Drainage, with its characteristic V-shaped river valleys, and into the Kern River drainage, where an ancient fault line has aided glaciers in the last ice age to create a U-shaped canyon that is almost perfectly straight for nearly 20 miles (32 km). On the floor of this canyon, at least two days hike from the nearest road, is the Kern Canyon hot spring, a popular resting point for weary backpackers. From the floor of Kern Canyon, the trail ascends again over 8,000 ft (2,400 m) to the summit of Mount Whitney. At Mount Whitney, the High Sierra Trail meets with the John Muir Trail and the Pacific Crest Trail, which continue northward along the Sierra crest and into the backcountry of Kings Canyon National Park.

Human history

The area which now comprises Sequoia National Park was first home to "Monachee" (Western Mono) Native Americans, who resided mainly in the Kaweah River drainage in the Foothills region of the park, though evidence of seasonal habitation exists as high as the Giant Forest. In the summertime, Native Americans would travel over the high mountain passes to trade with tribes to the East. To this day, pictographs can be found at several sites within the park, notably at Hospital Rock and Potwisha, as well as bedrock mortars used to process acorns, a staple food for the Monachee people. 

Tharp's Log, a cabin formed out of a hollowed-out giant sequoia log
 
By the time the first European settlers arrived in the area, smallpox had already spread to the region, decimating Native American populations. The first European settler to homestead in the area was Hale Tharp, who famously built a home out of a hollowed-out fallen giant sequoia log in the Giant Forest next to Log Meadow. Tharp allowed his cattle to graze the meadow, but at the same time had a respect for the grandeur of the forest and led early battles against logging in the area. From time to time, Tharp received visits from John Muir, who would stay at Tharp's log cabin. Tharp's Log can still be visited today in its original location in the Giant Forest.

However, Tharp's attempts to conserve the giant sequoias were at first met with only limited success. In the 1880s, white settlers seeking to create a utopian society founded the Kaweah Colony, which sought economic success in trading Sequoia timber. However, Giant Sequoia trees, unlike their coast redwood relatives, were later discovered to splinter easily and therefore were ill-suited to timber harvesting, though thousands of trees were felled before logging operations finally ceased.

The National Park Service incorporated the Giant Forest into Sequoia National Park in 1890, the year of its founding, promptly ceasing all logging operations in the Giant Forest. The park has expanded several times over the decades to its present size; one of the most recent expansions occurred in 1978, when grassroots efforts, spearheaded by the Sierra Club, fought off attempts by the Walt Disney Corporation to purchase a high-alpine former mining site south of the park for use as a ski resort. This site known as Mineral King was annexed to the park. Its name dates back to early 1873 when the miners in the area formed the Mineral King Mining District. Mineral King is the highest-elevation developed site within the park and a popular destination for backpackers.

Climate

According to the Köppen climate classification system, Sequoia National Park encompasses five climate types listed here from highest to lowest elevation; Tundra (ET), Mediterranean-influenced Subarctic climate (Dsc), Mediterranean-influenced warm-summer Humid continental climate (Dsb), Warm-summer Mediterranean climate (Csb), and Hot-summer Mediterranean climate (Csa). According to the United States Department of Agriculture, the Plant Hardiness zone at Giant Forest Visitor Center (6,444 ft (1,964 m)) is 8a with an average annual extreme minimum temperature of 12.0 °F (−11.1 °C).[13]

Climate data for Giant Forest Visitor Center, Sequoia National Park. Elev: 5646 ft (1721 m)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Average high °F (°C) 47.2
(8.4)
47.7
(8.7)
50.5
(10.3)
55.0
(12.8)
63.8
(17.7)
72.4
(22.4)
80.1
(26.7)
80.3
(26.8)
74.5
(23.6)
64.3
(17.9)
53.0
(11.7)
45.9
(7.7)
61.3
(16.3)
Daily mean °F (°C) 38.0
(3.3)
38.2
(3.4)
40.7
(4.8)
44.6
(7.0)
52.5
(11.4)
60.6
(15.9)
68.4
(20.2)
67.7
(19.8)
62.3
(16.8)
53.5
(11.9)
43.8
(6.6)
37.9
(3.3)
50.8
(10.4)
Average low °F (°C) 28.9
(−1.7)
28.8
(−1.8)
31.0
(−0.6)
34.3
(1.3)
41.3
(5.2)
48.8
(9.3)
56.7
(13.7)
55.2
(12.9)
50.2
(10.1)
42.6
(5.9)
34.6
(1.4)
29.8
(−1.2)
40.2
(4.6)
Average precipitation inches (mm) 7.59
(193)
7.16
(182)
6.81
(173)
3.61
(92)
1.78
(45)
0.67
(17)
0.33
(8.4)
0.14
(3.6)
0.71
(18)
1.96
(50)
4.32
(110)
6.11
(155)
41.19
(1,046)
Average relative humidity (%) 48.3 61.7 64.9 61.5 56.5 47.3 41.7 38.6 38.1 42.6 49.3 50.4 50.0
Average dew point °F (°C) 20.2
(−6.6)
26.2
(−3.2)
29.8
(−1.2)
32.2
(0.1)
37.5
(3.1)
40.4
(4.7)
44.2
(6.8)
41.6
(5.3)
36.4
(2.4)
31.3
(−0.4)
26.0
(−3.3)
21.1
(−6.1)
32.3
(0.2)

Geology

Sequoia National Park contains a significant portion of the Sierra Nevada. The park's mountainous landscape includes the tallest mountain in the contiguous United States, Mount Whitney, which rises to 14,505 feet (4,421 m) above sea level. The Great Western Divide parallels the Sierran crest and is visible at various places in the park, for example, Mineral King, Moro Rock, and the Giant Forest. Peaks in the Great Western Divide rise to more than 12,000 feet (3,700 m). Deep canyons lie between the mountains, including Tokopah Valley above Lodgepole, Deep Canyon on the Marble Fork of the Kaweah River, and Kern Canyon in the park's backcountry, which is more than 5,000 feet (1,500 m) deep for 30 miles (48 km).

 
Most of the mountains and canyons in the Sierra Nevada are composed of granitic rocks. These rocks, such as granite, diorite and monzonite, formed when molten rock cooled far beneath the surface of the earth. The molten rock was the result of a geologic process known as subduction. Powerful forces in the earth forced the landmass under the waters of the Pacific Ocean beneath and below an advancing North American Continent. Super-hot water driven from the subducting ocean floor migrated upward and melted rock as it proceeded. This process took place during the Cretaceous Period, 100 million years ago. Granitic rocks have a speckled salt-and-pepper appearance because they contain various minerals including quartz, feldspars and micas. Valhalla, or the Angel Wings, are prominent granitic cliffs that rise above the headwaters of the Middle Fork of the Kaweah River.

The Sierra Nevada is a young mountain range, probably not more than 10 million years old. Forces in the earth, probably associated with the development of the Great Basin, forced the mountains to rise. During the last 10 million years, at least four ice ages have coated the mountains in a thick mantle of ice. Glaciers form and develop during long periods of cool and wet weather. Glaciers move very slowly through the mountains, carving deep valleys and craggy peaks. The extensive history of glaciation within the range and the erosion resistant nature of the granitic rocks that make up most of the Sierra Nevada have together created a landscape of hanging valleys, waterfalls, craggy peaks, alpine lakes and glacial canyons.

Calcite formations in Crystal Cave
 
Park caves, like most caves in the Sierra Nevada of California, are mostly solutional caves dissolved from marble. Marble rock is essentially limestone that was metamorphosed by the heat and pressure of the formation and uplift of the Sierra Nevada Batholith. The batholith's rapid uplift over the past 10 million years led to a rapid erosion of the metamorphic rocks in the higher elevations, exposing the granite beneath; therefore, most Sierra Nevada caves are found in the middle and lower elevations (below 7,000 ft or 2,100 m), though some caves are found in the park at elevations as high as 10,000 ft (3,000 m) such as the White Chief cave and Cirque Cave in Mineral King. These caves are carved out of the rock by the abundant seasonal streams in the park. Most of the larger park caves have, or have had, sinking streams running through them.

The park contains more than 270 known caves, including Lilburn Cave which is California's longest cave with nearly 17 miles (27 km) of surveyed passages. The only commercial cave open to park visitors is Crystal Cave, the park's second-longest cave at over 3.4 miles (5.5 km). Crystal Cave was discovered on April 28, 1918 by Alex Medley and Cassius Webster. The cave is a constant 48 °F (9 °C), and is only accessible by guided tour.

Caves are discovered every year in the park with the most recently discovered major cave being Ursa Minor in August 2006.

Flora and Fauna

According to the A. W. Kuchler U.S. Potential natural vegetation Types, Sequoia National Park encompasses five classifications listed here from highest to lowest elevation; Alpine tundra & barren vegetation type with an Alpine tundra vegetation form...Pinus contorta/ Subalpine zone vegetation type with a California Conifer Forest vegetation form...Abies magnifica vegetation type with a California Conifer Forest vegetation form...Mixed conifer vegetation type with a California Conifer Forest vegetation form...and Chaparral vegetation type with a California chaparral and woodlands vegetation form.

Animals that inhabit this park are coyote, badger, black bear, bighorn sheep, deer, fox, cougar, eleven species of woodpecker, various species of turtle, three species of owl, opossum, various species of snake, wolverine, beaver, various species of frog, and muskrat.

Park attractions

Tunnel Tree in 1940
 
Crescent Meadow in the Giant Forest, called the "Gem of the Sierra" by John Muir
 
In addition to hiking, camping, fishing, and backpacking, the following attractions are highlights with many park visitors:
  • Sherman Tree Trail An 0.8-mile roundtrip paved trail that descends from the parking lot to the base of the General Sherman tree and meanders through a grove of giant sequoia trees.
  • Tunnel Log is a fallen giant sequoia tree in Sequoia National Park. The tree, which measured 275 feet (84 m) tall and 21 feet (6.4 m) in diameter, fell across a park road in 1937 due to natural causes. The following year, a crew cut an 8-foot (2.4 m) tall, 17-foot (5.2 m) wide tunnel through the trunk, making the road passable again.
  • Tokopah Falls The trail to Tokopah Falls starts just beyond the Marble Fork Bridge in Lodgepole Campground. It is an easy 1.7 mile (one way) walk along the Marble Fork of the Kaweah River to the impressive granite cliffs and waterfall of Tokopah Canyon. Tokopah Falls is 1,200 feet (365.8 meters) high, and is most impressive in early summer.
  • Crescent Meadow is a small, sequoia-rimmed meadow in the Giant Forest region of Sequoia National Park. This sierran montane meadow marks the western terminus of the High Sierra Trail, which stretches from the meadow across the Great Western Divide to Mount Whitney. Pioneer Hale Tharp homesteaded in this and nearby Log Meadow. Conservationist John Muir visited this meadow many times and praised it highly calling it the "Gem of the Sierra". The meadow lies at the end of a three-mile paved road which leaves the Generals Highway near the Giant Forest Museum.
  • Moro Rock is a granite dome located in the center of the park, at the head of Moro Creek, between Giant Forest and Crescent Meadow. A 400-step stairway, built in the 1930s by the Civilian Conservation Corps, is cut into and poured onto the rock, so that visitors can hike to the top. The stairway is listed on the National Register of Historic Places. The view from the rock encompasses much of the Park, including the Great Western Divide. It has an elevation of 6,725 feet (2,050 m).
  • Campgrounds in the park include three in the foothills area: Potwisha (42 sites), Buckeye Flat (28 sites), and South Fork (10 sites). Four campgrounds are at higher, conifer-dominated elevations, ranging from 6,650 to 7,500 feet (2,000 to 2,300 m): Atwell Mill (21 sites), Cold Springs (40 sites), Lodgepole (214 sites), and Dorst Creek (204 sites).
  • Giant Forest Museum offers information about giant sequoias and human history in the forest. The historic museum was built in 1928 by architect Gilbert Stanley Underwood.

Saguaro National Park

From Wikipedia, the free encyclopedia
  
Saguaro National Park
IUCN category II (national park)
Silhouettes of saguaro cacti stand out against a red sky at sunset.
Sunset in the Rincon Mountain District of the park
Map showing the location of Saguaro National Park
Map showing the location of Saguaro National Park
Location of Saguaro National Park in Arizona.
Inset: Arizona in the United States.
LocationTucson, Arizona, Pima, Arizona, United States
Coordinates32°10′45″N 110°44′13″WCoordinates: 32°10′45″N 110°44′13″W
Area91,716 acres (371.16 km2)
EstablishedOctober 14, 1994
Named forSaguaro, a cactus
Visitors957,405 (in 2018)
Governing bodyNational Park Service
WebsiteOfficial website

Saguaro National Park is an American national park in Pima County, southeastern Arizona. The 92,000-acre (37,000 ha) park consists of two separate areas—the Tucson Mountain District (TMD) about 10 miles (16 km) west of the city of Tucson and the Rincon Mountain District (RMD) about 10 miles (16 km) east of the city—that preserve Sonoran Desert landscapes, fauna, and flora, including the giant saguaro cactus.

The volcanic rocks on the surface of the Tucson Mountain District differ greatly from the surface rocks of the Rincon Mountain District; over the past 30 million years, crustal stretching displaced rocks from beneath the Tucson Mountains of the Tucson Mountain District to form the Rincon Mountains of the Rincon Mountain District. Uplifted, domed, and eroded, the Rincon Mountains are significantly higher and wetter than the Tucson Mountains. The Rincons, as one of the Madrean Sky Islands between the southern Rocky Mountains and the Sierra Madre Oriental in Mexico, support high biodiversity and are home to many plants and animals that do not live in the Tucson Mountain District.

Earlier residents of and visitors to the lands in and around the park before its creation included the Hohokam, Sobaipuri, Tohono O'odham, Apaches, Spanish explorers, missionaries, miners, homesteaders, and ranchers. In 1933, President Herbert Hoover, using the power of the Antiquities Act, established the original park, Saguaro National Monument, in the Rincon Mountains. In 1961, President John F. Kennedy added the Tucson Mountain District to the monument and renamed the original tract the Rincon Mountain District. Congress combined the Tucson Mountain District and the Rincon Mountain District to form the national park in 1994.

Popular activities in the park include hiking on its 165 miles (266 km) of trails and sightseeing along paved roads near its two visitor centers. Both districts allow bicycling and horseback riding on selected roads and trails. The Rincon Mountain District offers limited wilderness camping, but there is no overnight camping in the Tucson Mountain District.

Names

A large cactus (Carnegiea gigantea) at Saguaro National Park
 
The park gets its name from the saguaro (Carnegiea gigantea), a large cactus that is native to the Sonoran Desert and that does not grow naturally elsewhere. Rincón—as in Rincon Mountains, Rincon Creek, and Rincon Valley—is Spanish for corner, and refers to the shape of the mountain range and its footprint. The name Tucson derives from Papago-Piman words cuk ṣon [ˡtʃukʂɔn], meaning dark spring or brown spring. Tank or Tanque refers to a small artificial pool behind a dam that traps runoff in an existing natural depression. Madrean derives from Madre in Sierra Madre (Mother Mountains).

Geography

The park consists of two separate parcels, the Tucson Mountain District (TMD) to the west of Tucson, Arizona, and the Rincon Mountain District (RMD) to the east. Each parcel comes within about 10 miles (16 km) of the center of the city. Their total combined area in 2016 was 91,716 acres (37,116 ha). The Tucson Mountain District covers about 25,000 acres (10,000 ha), while the much larger Rincon Mountain District accounts for the balance of about 67,000 acres (27,000 ha). About 71,000 acres (29,000 ha) of the park, including large fractions of both districts, is designated wilderness.

Interstate 10, the major highway nearest to the park, passes through Tucson. Tucson Mountain Park abuts the south side of the Tucson Mountain District, and to its west lies the Avra Valley. The Rincon Mountain Wilderness, a separate protected area of about 37,000 acres (15,000 ha) in the Coronado National Forest, abuts the Rincon Mountain District on the east and southeast, while the Rincon Valley lies immediately south of the western part of the Rincon Mountain District.

Both districts conserve tracts of the Sonoran Desert, including ranges of significant hills, the Tucson Mountains in the west and the Rincon Mountains in the east. Elevations in the Tucson Mountain District range from 2,180 to 4,687 feet (664 to 1,429 m), the summit of Wasson Peak. Elevations within the Rincon Mountain District vary from 2,670 to 8,666 feet (814 to 2,641 m) at the summit of Mica Mountain.

Saguaro National Park lies within the watershed of the north-flowing Santa Cruz River, which is generally dry. Rincon Creek in the southern part of the Rincon Mountain District, free-flowing for at least part of the year, has the largest riparian zone in the park. The creek is a tributary of Pantano Wash, which crosses Tucson from southeast to northwest to meet Tanque Verde Wash. The two washes form the Rillito River, another dry wash, an east–west tributary of the Santa Cruz River. The washes in both districts are usually dry but are subject at times to flash floods. Smaller riparian zones are found near springs and tinajas in the Rincon Mountain District. The largest of the springs is at Manning Camp, high in the Rincons.

Climate

According to the Köppen climate classification system, Saguaro National Park has a Hot semi-arid climate (BSh). According to the United States Department of Agriculture, the Plant Hardiness zone at Red Hills Visitor Center 2,553 feet (778 m) is 9b with an average annual extreme minimum temperature of 25.8 °F (−3.4 °C), and 9a with an average annual extreme minimum temperature of 23.4 °F (−4.8 °C) at Rincon Mountain Visitor Center 3,091 feet (942 m).

Brief violent summer rains are sometimes accompanied by lightning, dust storms and flash floods. Some moisture at the highest elevations in the Rincons falls as snow in winter; snowmelt adds to the limited water available at lower elevations later in the year.

Studies of the effects of climate change on the park show that its annual mean temperature rose about 4 ℉ (2.2 C) from 1900 to 2010.

Climate data for Red Hills Visitor Center, Saguaro National Park. Elev: 2579 ft (786 m)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Average high °F (°C) 66.2
(19.0)
69.1
(20.6)
74.8
(23.8)
83.1
(28.4)
92.4
(33.6)
101.1
(38.4)
101.0
(38.3)
98.6
(37.0)
96.1
(35.6)
86.4
(30.2)
74.6
(23.7)
65.4
(18.6)
84.1
(28.9)
Daily mean °F (°C) 53.1
(11.7)
55.7
(13.2)
60.5
(15.8)
67.5
(19.7)
76.2
(24.6)
85.1
(29.5)
87.8
(31.0)
85.9
(29.9)
82.4
(28.0)
72.0
(22.2)
60.6
(15.9)
52.3
(11.3)
70.0
(21.1)
Average low °F (°C) 39.9
(4.4)
42.3
(5.7)
46.2
(7.9)
51.9
(11.1)
60.0
(15.6)
69.1
(20.6)
74.5
(23.6)
73.3
(22.9)
68.7
(20.4)
57.6
(14.2)
46.7
(8.2)
39.1
(3.9)
55.8
(13.2)
Average precipitation inches (mm) 0.97
(25)
0.92
(23)
0.90
(23)
0.34
(8.6)
0.19
(4.8)
0.30
(7.6)
1.99
(51)
2.51
(64)
1.09
(28)
0.94
(24)
0.58
(15)
1.00
(25)
11.73
(298)
Average relative humidity (%) 40.2 37.6 31.4 23.5 19.8 17.9 31.3 40.2 33.7 30.4 33.5 40.7 31.7
Average dew point °F (°C) 29.5
(−1.4)
30.2
(−1.0)
30.0
(−1.1)
28.9
(−1.7)
31.9
(−0.1)
36.7
(2.6)
53.7
(12.1)
58.9
(14.9)
51.0
(10.6)
39.2
(4.0)
31.7
(−0.2)
29.1
(−1.6)
37.6
(3.1)

Climate data for Rincon Mountain Visitor Center, Saguaro National Park. Elev: 3048 ft (929 m)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Average high °F (°C) 65.0
(18.3)
67.7
(19.8)
73.1
(22.8)
80.8
(27.1)
90.2
(32.3)
99.1
(37.3)
98.9
(37.2)
96.3
(35.7)
94.0
(34.4)
84.3
(29.1)
73.4
(23.0)
64.6
(18.1)
82.3
(27.9)
Daily mean °F (°C) 51.3
(10.7)
53.7
(12.1)
58.3
(14.6)
64.8
(18.2)
73.8
(23.2)
82.7
(28.2)
85.3
(29.6)
83.5
(28.6)
80.0
(26.7)
69.5
(20.8)
58.7
(14.8)
50.7
(10.4)
67.8
(19.9)
Average low °F (°C) 37.5
(3.1)
39.6
(4.2)
43.5
(6.4)
48.8
(9.3)
57.3
(14.1)
66.2
(19.0)
71.7
(22.1)
70.6
(21.4)
66.1
(18.9)
54.8
(12.7)
44.0
(6.7)
36.8
(2.7)
53.1
(11.7)
Average precipitation inches (mm) 1.15
(29)
1.15
(29)
1.15
(29)
0.36
(9.1)
0.24
(6.1)
0.26
(6.6)
2.57
(65)
2.63
(67)
1.37
(35)
1.17
(30)
0.75
(19)
1.24
(31)
14.04
(357)
Average relative humidity (%) 40.2 38.5 31.8 24.2 20.6 19.0 33.9 43.2 36.5 32.4 34.0 40.8 32.9
Average dew point °F (°C) 27.9
(−2.3)
29.0
(−1.7)
28.4
(−2.0)
27.3
(−2.6)
30.9
(−0.6)
36.3
(2.4)
53.7
(12.1)
58.8
(14.9)
51.0
(10.6)
38.7
(3.7)
30.4
(−0.9)
27.7
(−2.4)
36.7
(2.6)

Geology

Cacti and other desert plants surround a rock formation with horizontal banding.
Catalina gneiss, the most common rock type in the Rincons, is exposed at Javelina Rocks along the Cactus Forest Loop Drive in the Rincon Mountain District.

Saguaro National Park's oldest rocks, the Pinal Schist, pre-date the formation of the contemporary Basin and Range Province, of which the park is a part, by about 1.7 billion years. The schist is exposed in the Rincon Mountain District along a dry wash off Cactus Forest Loop Drive. Other ancient rocks, 1.4-billion-year-old altered granites, form much of Tanque Verde Ridge in the Rincon Mountain District.

Much later, about 600 million years ago, shallow seas covered the region around present-day Tucson; over time that led to deposition of sedimentary rockslimestones, sandstones, and shales. Limestone, which occurs in the park in several places, was mined here in the late 19th century to make mortar. The future park land had six lime kilns, two in the Tucson Mountain District, and four in the Rincon Mountain District. Three, all in the Rincon Mountain District, can be visited today—two along the Cactus Forest Trail and one along the Ruiz Trail.

About 80 million years ago tectonic plate movements induced a period of mountain building, the Laramide orogeny, which lasted until about 50 million years ago in western North America. Explosive volcanic eruptions formed the Tucson Mountains about 70 million years ago, and the roof of the volcano at their center collapsed to form a caldera 12 miles (19 km) across. The caldera was eventually filled by debris flows, the intrusion of a granitic pluton, and lava flows, some as recent as 30 to 15 million years ago. Volcanic rocks exposed in and near the Tucson Mountain District are remnants of these events. Examples include large breccia exposed at Grants Pass and a granitic remnant of the magma chamber, which is visible from the Sus Picnic Area in the Tucson Mountain District. Not all of the molten granite reached the surface of the Tucson Mountains; some cooled and crystallized far below.

The Tucson Basin and nearby mountains—including the Tucson Mountains to the west, the Santa Catalinas to the north, and the Rincons to the east—are part of the Basin and Range Province extending from northern Mexico to southern Oregon in the United States. The province, of relatively recent geologic origin, formed when plate movements stretched and thinned the Earth's crust in this part of western North America until the crust pulled apart along faults. The Catalina Fault, a low-angle detachment fault, began to form about 30 million years ago about 6 to 8 miles (10 to 13 km) below the surface of the Tucson Mountains. The rocks under the fault, the lower-plate rocks, were eventually displaced 16 to 22 miles (26 to 35 km) east-northeast relative to the rocks above the fault, then uplifted, domed, and eroded to form the Santa Catalina and Rincon mountains visible today. Although the volcanic rocks seen on the surface of the Tucson Mountain District are not found in the Rincon Mountain District, the crystallized granite (Catalina gneiss) from beneath the Tucson Mountains was eventually exposed on the Rincon Mountain District's surface. The most common rock type in the Rincon Mountains, this banded gneiss is visible in the Rincon Mountain District at sites such as Javelina Rocks along the Cactus Forest Loop Drive.

History

Early

Engravings of animals and people adorn the vertical face of a rock formation.
Hohokam petroglyphs in the Tucson Mountain District
 
The earliest known residents of the land in and around what later became Saguaro National Park were the Hohokam, who lived there in villages between 200 and 1450 A.D. Petroglyphs and bits of broken pottery are among Hohokam artifacts found in the park. The Hohokam hunted deer and other animals, gathered cholla buds, prickly pears, palo verde pods, and saguaro fruit, and grew corn, beans, and squash. Subsequent indigenous cultures, the Sobaipuri of the Tucson Basin and the Tohono O'odham to the west, may be descendants of the Hohokam, though the evidence is inconclusive.

Spanish explorers first entered Arizona in 1539–40. Non-native settlement of the region near the park did not occur until 1692 with the founding of San Xavier Mission along the Santa Cruz River, which flowed through Tucson. In 1775, the Spaniards built Presidio San Agustín del Tucsón, a military fort in what was then part of New Spain, in part to protect against raids by Apaches.

The lands that eventually would become Saguaro National Park remained relatively free of development until the mid-19th century, after Arizona had become part of the United States. After passage of the Homestead Act of 1862, the arrival of the railroad in 1880, and the end of the Apache Wars in 1886, homesteaders and ranchers established themselves in the Tucson and Rincon Mountains, and miners sought silver, copper, and other valuable ores and minerals. Mining in the park continued intermittently through 1942, while ranching on private in-holdings within the park continued until the mid-1970s.

The defunct Loma Verde Mine, which is still visible in the Rincon Mountain District, produced a small amount of copper and gold between 1897 and 1907. Mining of igneous rock at 149 sites in the Tucson Mountain District sometimes produced ores of modest value in the late 19th and early 20th centuries.[47] The most successful, the Copper King Mine (later renamed the Mile Wide Mine), yielded 34,000 tons of copper, gold, lead, zinc, and molybdenum ores, mostly during the war years of 1917, 1918, and 1941; it closed permanently in 1942 when it became unprofitable.

Ranchers grazed thousands of cattle on public land that would later become part of the park, and homesteaders farmed and ranched at the base of the Rincons, filing homestead applications from the 1890s through 1930. The remains of the former Freeman Homestead, established in 1929, lie along a nature trail in the Rincon Mountain District. The homestead is on the Arizona State Register of Historic Places. Manning Cabin, built in 1905 as a summer retreat for Levi Manning, a wealthy businessman and one-term mayor of Tucson, is part of the infrastructure at Manning Camp near Mica Mountain. Modified and restored after falling into disrepair, it was added to the National Register of Historic Places in 1975. Cultural resources in the park include more than 450 archeological sites and more than 60 historic structures.

After 1920

Hundreds of saguaro cacti and many other desert plants grow on a flat plain at the base of an apparently barren mountain.
Saguaro National Monument (now the Rincon Mountain District) in 1935
 
In 1920 members of the Natural History Society of the University of Arizona expressed interest in establishing a protected area for saguaro, a cactus species familiar to watchers of silent-movie Westerns. In 1928 Homer L. Shantz, a plant scientist and the university's president, joined the efforts to create a saguaro sanctuary, but issues related to funding and management delayed the creation of a park. In 1933 Frank Harris Hitchcock, publisher of the Tucson Citizen and a former United States Postmaster General who was influential in the Republican Party, persuaded U.S. President Herbert Hoover to create Saguaro National Monument. Hoover used his power under the Antiquities Act of 1906 to create the monument by proclamation on March 1, 1933. Later that year President Franklin D. Roosevelt transferred management of the monument, east of Tucson in the Rincon Mountains, to the National Park Service. Between 1936 and 1939, during the Roosevelt administration, the Civilian Conservation Corps (CCC) built the monument's Cactus Forest Loop Drive and related infrastructure. The monument's visitor center opened in the 1950s.

In 1961 President John F. Kennedy—encouraged by Stewart Udall, an Arizonan who was then Secretary of the Interior—added 16,000 acres (6,500 ha) of cactus lands in the Tucson Mountains to the monument. This western district of the monument was carved from Tucson Mountain Park, managed by Pima County. In the 1920s, the Tucson Game Protective Association had persuaded the Department of the Interior to withdraw about 30,000 acres (12,000 ha) in the Tucson Mountains from homesteading and mining and to set it aside as a park and game refuge. Land leased by the county in this set-aside became the Tucson Mountain Recreation Area in 1932. Between 1933 and 1941 CCC workers built structures at eight picnic areas in the county-park portion of the set-aside, five of which later became part of the Tucson Mountain District of the national monument. Their other projects involved road- and trail-building, landscaping, erosion control, and enhancing water supplies for wildlife. Kennedy's 1961 proclamation created the Tucson Mountain District from the northern part of the county park and renamed the original monument lands east of Tucson the Rincon Mountain District.[13] Expansions in 1976 and 1994 brought the total Tucson Mountain District area to 24,818 acres (10,043 ha). In 1994 Congress elevated the combined Tucson Mountain District and Rincon Mountain District to National Park status.

A sparsely vegetated range of mountains rises above a populated area with trees, shrubs, and cacti.
Panorama of the Rincon Mountains. The houses and vegetation in the foreground are in Pima County, a few blocks east of the eastern boundary of Tucson.

Biology

Plants and fungi

A close-up of a desert shrub in bloom. The flower is a cluster of light pink filaments radiating from a dark pink center.
Fairy duster, a low flowering shrub native to the park

According to the A. W. Kuchler U.S. Potential natural vegetation Types, Saguaro National Park encompasses four classifications; a Parkinsonia/Cactus (43) vegetation type with a Deserts and xeric shrublands (8) vegetation form, a Creosote bush scrub/Ragweed (42) vegetation type with a Deserts and xeric shrublands (8) vegetation form, a Bouteloua/Pleuraphis mutica Steppe (58) vegetation type with a Desert Steppe (14) vegetation form, and an Oak/Juniper Woodland (31) vegetation type with a Great Basin montane forests/Southwest Forest (4) vegetation form.

Plant communities within the park vary with elevation. The Tucson Mountain District has two distinct communities, desert scrub—such as fourwing saltbush and brittlebrush—at the lowest elevations, and desert grassland a little higher. The Rincon Mountain District includes these two communities as well as four more at higher elevations, oak woodland, pine–oak woodland, pine forest and, high in the Rincons, mixed conifer forestDouglas-fir, Ponderosa pine, white fir, Gambel oak, and many other trees, shrubs, and understory plants. During annual inventories in 2011 and 2013, hundreds of scientists and thousands of volunteers identified 389 species of vascular plants, 25 of non-vascular plants, and 197 species of fungi in Saguaro National Park.

Saguaros, which flourish in both districts of the park, grow at an exceptionally slow rate. The first arm of a saguaro typically appears when the cactus is between 50 and 70 years old though it may be closer to 100 years in places where precipitation is very low. Saguaros may live as long as 200 years and are considered mature at about age 125. A mature saguaro may grow up to 60 feet (18 m) tall and weigh up to 4,800 pounds (2,200 kg) when fully hydrated. The total number of saguaros in the park is estimated at 1.8 million, and 24 other species of cactus are abundant. The most common of these are the fishhook barrel, staghorn cholla, pinkflower hedgehog, Engelman's prickly pear, teddybear cholla, and jumping cholla.

Invasive plants include fountain grass, tamarisk, Malta starthistle, and many others, but by far the most severe threat to the native ecosystem is buffelgrass. This drought-tolerant plant, native to parts of Africa and Asia, was imported to the United States in the 1930s and planted near Tucson and elsewhere to create cattle forage and to control erosion. First detected in the park in 1989, it has dispersed widely in both districts. Competing with other plants for sustenance, buffelgrass fills the empty spaces normally found between native desert plants and creates a significant fire hazard. The noxious weed, considered impossible to completely eliminate, is managed in some areas of the park and in Tucson residential zones by hand-pulling and, during periods of wet weather, application of glyphosate-based herbicides.

A view of Saguaro National Park's natural landscape.

Animals

A dark brown hoofed animal with a long snout stands on a plot of dry ground near the shadow of a tree.
Javelina in Saguaro National Park. The hoofed animal is native to the park.
 
An inventory of medium and large mammals in the park confirmed the presence of 30 species in Saguaro National Park between 1999 and 2008. Of these, 21 were found in the Tucson Mountain District and 29 in the Rincon Mountain District. A partial list of the park's mammals includes cougars, coyotes, bobcats, white-tailed deer, mule deer, javelinas, gray foxes, black-tailed jackrabbits, desert cottontails, ring-tailed cats, white-nosed coatis, ground squirrels, and packrats. One endangered mammal, the lesser long-nosed bat, lives part of the year in the park and part of the year in Mexico.

The wide range of habitats in the park supports a diverse population of birds including some, such as the vermilion flycatcher and the whiskered screech owl, uncommon elsewhere in the United States.[69] Among the park's 107 bird species are great horned owls, cactus wrens, ravens, kestrels, turkey vultures, roadrunners, woodpeckers, hawks, quails, and hummingbirds, and one threatened species, the Mexican spotted owl.

The park's 36 reptile species include desert tortoises, diamondback rattlesnakes (one of the more commonly seen snakes), coral snakes, Gila monsters, short-horned lizards, spiny lizards, and zebra-tailed lizards. Despite the aridity, three amphibian species inhabit the park: the canyon tree frog, the lowland leopard frog, and Couch's spadefoot, which lives in burrows, emerging to breed during summer rains. Forest fires, which create erosion-prone burned areas, have destroyed many of the leopard frog's breeding pools, which fill with sediment. The Arizona Game and Fish Department lists the lowland leopard frog as a species of special concern.

Urban sprawl, air and water pollution, noise, light pollution, and a range of habitat restricted by human infrastructure put stress on the park's mammals and other animals, but the most serious immediate threat to them is roadkill. About 50,000 vertebrates a year die on the park's roads when they are hit by a vehicle. The Rincon Mountain District has few roads, but Picture Rocks Road, an east–west commuter highway crossing the Tucson Mountain District, is highly dangerous to wildlife. Attempts in 2002 to convert it to a hiking trail failed after the proposal met with stiff public resistance.

Sky Islands

The Rincons and the nearby Santa Catalinas (but not the shorter Tucson Mountains) are among about 40 mountain ranges known as the Madrean Sky Islands that are of special interest to biologists. These ranges, resembling a series of stepping stones between the southern end of the Rocky Mountains—specifically the Mogollon Rim of the Colorado Plateau—in the United States and the Sierra Madre Occidental in Mexico, are continental "islands" separated from one another by "seas" of lower-elevation valleys that impede but do not completely block species migration from one sky island to another. Ecologist Peter Warshall lists several characteristics that make the Madrean complex unique among Earth's 20 or so sky-island complexes. Among these are its north–south orientation across eight degrees of latitude spanning zones from the temperate to the subtropical, the highly varied nature of its geologic origin and of its soils, the moderate to high relief of its terrain, and its safe distance from the mass extinctions related to the northern glaciers of the most recent Ice Age. Influenced by these and other conditions, the Madrean Sky Islands support unusual biodiversity.

Recreation

The park is generally open to hikers all day every day except Christmas; the Tucson Mountain District is open to vehicle traffic from sunrise to sunset and the Rincon Mountain District from 7 a.m. to sunset. Both districts have visitor centers. More than 165 miles (266 km) of hiking trails wind through the park, where perils may include extreme heat, dehydration, flash floods, cactus spines, snakes, cougars, bears, and Africanized bees. The Rincon Mountain District is open to wilderness camping, which requires a permit, but no overnight camping is permitted in the Tucson Mountain District.

Tucson Mountain District

Map of the Tucson Mountain District, an irregular squarish shape colored green and surrounded by brown or gold-shaded areas not in the park
Map of the Tucson Mountain District showing entrances, roads, buildings, trails, picnic areas, and surrounds
 
The Tucson Mountain District has 12 miles (19 km) of paved roads and 8.5 miles (13.7 km) of unpaved roads, including the 5-mile (8 km) Bajada Loop Drive. Bicycling is allowed only on paved roads, as well as Bajada Loop Drive, Golden Gate Road, and the Belmont multi-use trail. Horses and other livestock are allowed on some of the trails.

Hohokam petroglyphs etched into large stones are easily accessible in the Tucson Mountain District. The Signal Hill Trail, which begins at the Signal Hill Picnic Area along the Bajada Loop Drive, leads to an area with dozens of examples of the 800-year-old rock art.

Among the notable artificial structures in the Tucson Mountain District are ramadas, picnic tables, and restrooms built by the Civilian Conservation Corps between 1933 and 1941. Designed to conform to their natural surrounds, the rustic buildings consist mainly of quarried stone and other materials native to the area.

The Arizona-Sonora Desert Museum lies just south of the Tucson Mountain District along North Kinney Road in Tucson Mountain County Park. The non-profit organization, operating on 98 acres (40 ha) rented from Pima County, combines aspects of a botanical garden, zoo, and natural history museum featuring the plants and animals native to the region.

Rincon Mountain District

Map of the Rincon Mountain District, an irregular retangle, wider than long, colored green, and surrounded by areas colored brown or light purple that are outside the park
Map of the Rincon Mountain District showing entrances, roads, buildings, trails, picnic areas, campsites, and surrounds

The Rincon Mountain District features the 8.3-mile (13.4 km) Cactus Forest Loop Drive, which provides access to some of the trails. Angling across the Rincon Mountain District from southwest to northeast is a segment of the Arizona Trail. The 800-mile (1,300 km) trail crosses Arizona from its border with Mexico on the south to its border with Utah on the north. In 2009, Congress named it a National Scenic Trail.

Horseback riding is allowed on some of the trails. Livestock—defined by the NPS as horses, mules, or burros—must carry their own food and are not allowed to graze in the park. Bicycling is allowed on the Cactus Forest Loop Drive and two park trails.

Manning Camp Campground is the main staging area for firefighters, trail-maintenance crews, and scientists working in the Rincon Mountain District. Their supplies are brought in by pack mules that are kept in corrals at the site. Runoff from a nearby spring, the largest in Rincons, provides water for the livestock.

On a 40-acre (16 ha) plot adjacent to the Rincon Mountain District along Broadway, the Desert Research Learning Center (DRLC) supports scientific and educational projects related to a network of Sonoran Desert parks, including Saguaro National Park. The DRLC grounds, which include desert plants, an artificial tinaja, and a rainwater collection system, are open to the public. The Sonoran Desert Inventory and Monitoring Network of which the DRLC is part, covers 10 national monuments or parks in Arizona and 1 in New Mexico.

Human extinction

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