Yellowstone 黄石公园 - Grand Prismatic Spring

Yellowstone National Park spans an area of 3,468.4 square miles (8,983 km2), comprising lakes, canyons, rivers and mountain ranges. Yellowstone Lake is one of the largest high-elevation lakes in North America and is centered over the Yellowstone Caldera, the largest supervolcano on the continent. The caldera is considered an active volcano. It has erupted with tremendous force several times in the last two million years. Half of the world's geothermal features are in Yellowstone, fueled by this ongoing volcanism. Lava flows and rocks from volcanic eruptions cover most of the land area of Yellowstone. The park is the centerpiece of the Greater Yellowstone Ecosystem, the largest remaining nearly-intact ecosystem in the Earth's northern temperate zone.

黄石国家公园是美国第一个国家公园。主要位于怀俄明州，部分位于蒙大拿州和爱达荷州，于1872年3月1日美国总统尤利西斯·辛普森·格兰特签署国会通过的法案后建立，是世界上第一个国家公园。黄石公园以其丰富的野生动物种类和地热资源闻名，老忠实间歇泉更是其中最富盛名的景点之一。公园中有着多种类型的生态系统，其中以亚高山带森林为主。

美洲原住民已经在黄石公园地区生活了至少1万1千年，19世纪早期的刘易斯与克拉克远征也绕过了这一区域。对该地区的有组织的勘探活动直到1860年代末才开始出现，此前只有一些选择在野外捕猎和居住的山地人在19世纪早期到中叶曾偶尔进入。美国陆军在公园刚刚建立后就受委托对其进行监管。1917年后，公园的管理工作移交给了之前一年刚刚成立的美国国家公园管理局。园中有数以百计因其建筑学和历史学意义而保护起来的建筑物，研究人员已经发现了超过1000个考古遗迹。

黄石国家公园占地面积约为8983平方千米，其中包括湖泊、峡谷、河流和山脉。公园内最大的湖泊是位于黄石火山中心的黄石湖，是整个北美地区最大的高海拔湖泊之一。黄石火山是北美最大且仍处于活跃状态的超级火山，在过去两百万年中它曾数次以巨大的力量爆发。喷出的熔岩和火山灰也覆盖了公园内的绝大部分地区。得益于其持续的活跃状态，世界上的地热资源有半数位于黄石公园地区。黄石公园也是大黄石生态系统的核心所在，这是北温带地区现存最大且仍然近乎完好的自然生态系统。

公园内有记录的哺乳动物、鸟类、鱼类和爬行动物有数百种之多，其中包括多种濒危或受威胁物种，广袤的森林和草原中同样存有多种独特的植物。黄石公园是美国本土最大和最著名的巨型动物居住地。公园中有灰熊、狼、美洲野牛和加拿大马鹿的栖息地。黄石公园野牛群是美国最古老也最大的野牛群。公园内每年都会发生山火，其中最大的一次是1988年黄石公园大火，公园内近三分之一的面积被烧毁。黄石公园也是休闲娱乐的好去处，园内可进行远足、露营、划船、钓鱼、度假和观光等活动。沿着园内铺设的道路可以就近接触到主要的地热区域以及一些湖泊和瀑布。冬天，游客们则往往会在导游指引下乘坐雪上摩托车等冰上交通工具来造访公园。

Grand Prismatic Spring 大棱镜温泉

Aerial view 鸟瞰图

The Grand Prismatic Spring in Yellowstone National Park is the largest hot spring in the United States, and the third largest in the world,  after Frying Pan Lake in New Zealand and Boiling Lake in Dominica. It is located in the Midway Geyser Basin.

Grand Prismatic Spring was noted by geologists working in the Hayden Geological Survey of 1871, and named by them for its striking coloration. Its colors match the rainbow dispersion of white light by an optical prism: red, orange, yellow, green, and blue.

大棱镜温泉也是黄石公园里最有名的间歇泉之一。大棱镜温泉的美在于湖面的颜色随季节而改变，春季，湖面从绿色变为灿烂的橙红色，这是由于富含矿物质的水体中生活着的藻类和含色素的细菌等微生物，它们体内的叶绿素和类胡萝卜素的比例会随季节变换而改变，于是水体也就呈现出不同的色彩。在夏季，叶绿素含量相对较低，显现橙色、红色，或黄色。但到了冬季，由于缺乏光照，这些微生物就会产生更多的叶绿素来抑制类胡萝卜素的颜色，于是就看到水体呈现深绿色。

Excelsior Geyser

Yellowstone 黄石公园 - The Grand Canyon

黄石大峡谷（Yellowstone National Park Grand Canyon）位于美国黄石国家公园，在黄石国家公园90处观光景点中排名第1。

美国黄石公园里黄石湖流出的河水，流过一段平缓的丘陵地带后，进入一段长约38公里的险峻峡谷，被称为黄石大峡谷。这里是黄石公园最壮丽、最华美的景色之一。 在这里，湍急的河水浪花飞溅，形成两道壮丽的瀑布，轰鸣着泄人谷底。第一个瀑布有33米高，这是上瀑布（Upper Falls），第二个有92米高，称为下瀑布（Lower Falls）。

黄石大峡谷是由黄石河冲蚀被地热腐蚀的火山岩形成。大约在14000到18000年前，大峡谷又连接经历了三次冰川的侵蚀，逐渐形成这种典型的V型（river-eroded）峡谷。黄石大峡谷大约在10000年前才形成当今的模样，可以说它还是相当年轻。

The Grand Canyon of the Yellowstone is the first large canyon on the Yellowstone River downstream from Yellowstone Falls in Yellowstone National Park in Wyoming. The canyon is approximately 24 miles (39 km) long, between 800 and 1,200 ft (240 and 370 m) deep and from .25 to .75 mi (0.40 to 1.21 km) wide.

The specifics of the geology of the canyon are not well understood, except that it is an erosional feature rather than the result of glaciation. After the Yellowstone Caldera eruption of about 600,000 years ago, the area was covered by a series of lava flows. The area was also faulted by the doming action of the caldera before the eruption. The site of the present canyon, as well as any previous canyons, was probably the result of this uplift and related faulting, which allowed erosion to proceed at an accelerated rate. The area was also covered by the glaciers that formed during several ice ages. Glacial deposits probably filled the canyon at one time, but have since been eroded away, leaving little or no evidence of their presence.

The canyon below the Lower Yellowstone Falls was at one time the site of a geyser basin that was the result of rhyolite lava flows, extensive faulting, and heat beneath the surface (related to the hot spot). No one is sure exactly when the geyser basin was formed in the area, although it was probably present at the time of the last glaciation. The chemical and heat action of the geyser basin caused the rhyolite rock to become hydrothermally altered, making it very soft and brittle and more easily erodible (sometimes likened to baking a potato). Evidence of this thermal activity still exists in the canyon in the form of geysers and hot springs that are still active and visible. The Clear Lake area, which is fed by hot springs, south of the canyon is probably also a remnant of this activity. According to Ken Pierce, U.S. Geological Survey geologist, at the end of the last glacial period, about 14,000 to 18,000 years ago, ice dams formed at the mouth of Yellowstone Lake. When the ice dams melted, a great volume of water was released downstream causing massive flash floods and immediate and catastrophic erosion of the present-day canyon. These flash floods probably happened more than once. The canyon is a classic V-shaped valley, indicative of river-type erosion rather than glaciation. Today the canyon is still being eroded by the Yellowstone River.

he colors in the canyon are also a result of hydrothermal alteration. The rhyolite in the canyon contains a variety of different iron compounds. When the old geyser basin was active, the "cooking" of the rock caused chemical alterations in these iron compounds. Exposure to the elements caused the rocks to change colors. The rocks are oxidizing; in effect, the canyon is rusting. The colors indicate the presence or absence of water in the individual iron compounds. Most of the yellows in the canyon are the result of iron present in the rock rather than, as many people think, sulfur.