Grand Canyon and Grand Staircase

大峡谷和大阶梯

A showcase of the history of sedimentary rock

沉积岩历史的展示

The Grand Canyon and the layered formations north of it to Zion Canyon and Bryce Canyon display the history of sedimentary rock through much of Earth's history. The formations rise in what is often called the "grand staircase". The multiple layers offer an opportunity to survey many types of sedimentary formations. The illustration below will be used as a key to the discussion of the multiple formations. This illustration is patterned after one in "The Grand Canyon", C. Hill, et al., eds, Figure 3-2 and a similar color scheme is followed for organization of the comments.

大峡谷及其北侧的层状岩层，直至祖尼峡谷和布莱克峡谷，展示了地球历史上大部分时间的沉积岩历史。这些岩层呈现出所谓的“伟大阶梯”。多层结构为观察多种沉积岩层提供了机会。下图将用于讨论这些多种岩层的说明。该图是根据《大峡谷》（C. Hill 等编，图3-2）改编的，采用类似的配色方案来组织评论。

Because the Grand Canyon exposes a large fraction of the Earth's geologic history, it has been the subject of intensive study. A recent review of studies up to 2020 by Karlstrom, Crossey, Mathis and Bowman, Telling Time at Grand Canyon National Park, summarizes the efforts to accurately date the features of the Canyon. An even more recent review of this material can be found in the National Park Service's website which is beautifully illustrated and includes updates on the "Telling Time .." article.

Active Graphic

Claron Formation

Claron 岩层

The Claron Formation is a lake deposit (limestone) from the Cenozoic Era containing fossils of freshwater fish and an abundance of fossils of freshwater snails.(Hill,et al.,Ch3) The unique pillars of Bryce Canyon, called hoodoos, are carved into this formation. There are fossils of animals like bison and of flowering plants, but none of the extinct species such as trilobites and dinosaurs.(Hill,et al.,Ch4)

克拉伦组是一种晚太古代时期的湖泊沉积物（石灰岩），其中含有淡水鱼和大量淡水蜗牛的化石。（Hill等，第3章） Bryce Canyon独特的石柱被称为石笋，是由这种沉积物雕刻而成的。其中含有类似野牛的动物化石和开花植物的化石，但没有三叶虫和恐龙等灭绝物种的化石。（Hill等，第4章）

Caanan Peak Formation

卡纳安峰形成

Named for exposures of this formation around Caanan Peak, this formation is mostly a coarse clastic unit characterized by gray, tan, light-brown and pink conglomerates and conglomeratic sandstones. The material is thought to be associated with river and stream deposition and varies in thickness from about 40ft to 1000 ft. It sits atop the Kaiparowits Formation but is mostly absent in the Bryce Canyon area. It is associated with the Paleocene epoch. USGS report, Wiki

Kaiparowits Formation

Kaiparowits Formation（矿物名）

The Kaiparowits Formation is placed in the Mesozoic Era, Cretaceous Period. The fossils found there are terrestrial fossils: frogs, lizards, turtles, crocodiles, duckbill dinosaurs, horned dinosaurs, theropod dinosaurs, and marsupial mammals. (Hill,et al.,Ch13) It is characterized by gray sandstones and mudstones, and is in the neighborhood of 100ft (30m) thick in the Bryce Canyon area. Wiki

以Caanan Peak附近暴露的沉积物命名，这一地层主要由粗粒碎屑岩组成，特征为灰色、浅黄、浅棕色和粉红色的砾岩和碎屑质砂岩。该沉积物被认为与河流和溪流沉积有关，厚度从约40英尺到1000英尺不等。它位于Kaiparowits地层之上，但在Bryce Canyon地区大多缺失。它与白垩纪时期有关。USGS报告，维基百科将Kaiparowits地层归入中生代白垩纪时期。在那里发现的化石是陆生化石：青蛙、蜥蜴、乌龟、鳄鱼、鸭嘴龙、有角恐龙、兽脚类恐龙和有袋类哺乳动物。（Hill等，第13章）其特征为灰色砂岩和泥岩，并且在Bryce Canyon地区厚度约为100英尺（30米）。维基百科

Wahweap Formation

瓦赫韦普形成

The Wahweap Formation is placed in the Mesozoic Era, Cretaceous Period. It has sandstone and siltstone and is the source of a significant variety of invertebrate fossils: insect burrows in petrified logs, mollusks, crabs, gastropods. Freshwater fish fossils have been recovered: bowfin, rays, probable lungfish burrows. Several dinosaur fossils have been found: hadrosaur, ceratopsian, theropod. Wiki.

Straight Cliffs Formation

直立峭壁构造

The Straight Cliffs Formation is placed in the Mesozoic Era, Cretaceous Period. The fossils found there are terrestrial fossils: frogs, lizards, turtles, crocodiles, duckbill dinosaurs, horned dinosaurs, theropod dinosaurs, and marsupial mammals. (Hill,et al.,Ch13)

Tropic Shale

热带页岩

The Tropic Shale formation is placed in the Mesozoic Era, Cretaceous Period. Fossils found there include ammonites, sharks and plesiosaurs. (Hill,et al.,Ch13)

三叠纪时期的特里克 shale 地层中发现了鹦鹉螺、鲨鱼和海龙兽的化石。（Hill 等，第13章）

瓦赫普组位于中生代的白垩纪时期，由砂岩和淤岩组成，是多种无脊椎动物化石的来源：包括在化石木中的昆虫穴居、软体动物、螃蟹和双壳类。已发现的淡水鱼类化石包括弓鳍鱼、鳐鱼和可能的肺鱼穴居。已发现几种恐龙化石：鸭嘴龙、角龙类和兽脚类恐龙。维基。直崖组位于中生代的白垩纪时期。该地发现的化石为陆生化石：青蛙、蜥蜴、龟类、鳄鱼、鸭嘴恐龙、角龙类恐龙、兽脚类恐龙和有袋类哺乳动物。（Hill等，第13章）

Dakota Formation

达科塔组

由于大峡谷暴露了地球地质历史的大部分，它已成为研究的热点。Karlstrom、Crossey、Mathis 和 Bowman 于 2020 年前的研究综述《大峡谷国家公园的计时》总结了对峡谷特征进行准确定年的努力。更近期的综述可参见国家公园管理局的网站，该网站图文精美，并包含对‘计时’文章的更新。Active Graphic

The Dakota Formation is placed in the Mesozoic Era, Cretaceous Period. Fossil pollen and spores have been collected here. (Hill,et al.,Ch14)

Entrada Formation

入口形成

The Entrada Formation is placed in the Mesozoic Era, Jurassic Period. The fossils found there are dinosaur bones and tracks. (Hill,et al.,Ch13)

Carmel Formation

卡梅尔岩层

达科他组被归入中生代的白垩纪时期。这里发现了化石花粉和孢子。（Hill等，第14章）恩塔达组被归入中生代的侏罗纪时期。在那里发现的化石是恐龙骨骼和足迹。（Hill等，第13章）

The Carmel Formation (limestone) dating to the Mesozoic Era, Jurassic Period, contains many fossil examples of marine fauna. There are many marine invertebrates including corals, crinoids, oysters and other bivalves, and the extinct cephalopods known as ammonites. (Hill,et al.,Ch13)

Temple Cap Formation

庙顶形成

Navajo Sandstone

纳瓦霍砂岩

The Navajo Sandstone is placed in the Mesozoic Era, Jurassic Period. The fossils found there are dinosaur bones and tracks. (Hill,et al.,Ch13)

Kayenta Formation

凯恩塔 Formation

The Kayenta Formation is placed in the Mesozoic Era, Jurassic Period. The fossils found there are dinosaur bones and tracks. (Hill,et al.,Ch13)

Moenave Formation

Moenave Formation（矿物名）

Wingate Sandstone

Wingate砂岩

Chinle Formation

钦勒期

卡梅尔组（石灰岩）可追溯至中生代的侏罗纪时期，包含许多海洋动物的化石。其中包括许多海洋无脊椎动物，如珊瑚、海葵、牡蛎和其他双壳类动物，以及已灭绝的头足类动物——菊石。（Hill等，第13章）纳瓦霍砂岩被归类于中生代的侏罗纪时期。该地发现的化石是恐龙的骨骼和足迹。（Hill等，第13章）凯伊塔组被归类于中生代的侏罗纪时期。该地发现的化石也是恐龙的骨骼和足迹。（Hill等，第13章）

"The Chinle Formation s placed in the Mesozoic Era, Triassic Period. It consists of colorful mudstones and siltstones that erode to form the low, rounded hills of Arizona's Painted Desert and Petrified Forest National Park."(Hill,et al.,Ch13) Fossils preserved here are many primitive conifer trees and several groups of plants that do not appear in underlying Paleozoic rocks. There are also fossils of insects and scorpions, freshwater fish and a variety of tetrapods. There are fossils of early dinosaurs. Hill, et al. lists freshwater clams, crayfish, beetles, lungfish, phytosaurs, aetosaurs, and an early bipedal dinosaur, Coelophysis. No marine organisms of any kind have been found in the Chinle Formation.

Moenkopi Formation

莫恩科皮岩层

The Moenkopi Formation is placed in the Mesozoic Era, Triassic Period. The fossils found there are mostly terrestrial fossils. Findings include large amphibians, tracks, and coelacanth fish. (Hill,et al.,Ch13)

Kaibab Formation

卡布 Formation

The Kaibab Formation is placed in the Paleozoic Era, Permian Period. The fossils found there are marine fossils: sponges, corals,brachiopods, bryozoans, gastropods, pelecypods, nautiloids, sharks and bony fish. Trilobites are found, but are rare.(Hill,et al.,Ch13) The projected age is 270 Myr (Hill et. al., Karlstom, et. al.).

Toroweap Formation

Toroweap Formation（矿物名）

The Toroweap Formation is placed in the Paleozoic Era, Permian Period. The fossils found there are marine fossils: sponges, corals,brachiopods, bryozoans, gastropods, pelecypods, nautiloids, sharks and bony fish. Trilobites are found, but are rare.(Hill,et al.,Ch13) The projected age is 275 Myr (Karlstom, et. al.).

Coconino Sandstone

科科尼诺砂岩

The Coconino Sandstone is placed in the Paleozoic Era, Permian Period. The fossils found there are terrestrial fossils: tracks of reptiles, spiders and scorpions. No marine fossils are found there, in contrast to lower levels. (Hill,et al.,Ch13) Fossil pollen from conifer-like (non-flowering) trees is found here. (Hill,et al.,Ch14) The projected age is 280 Myr.(Karlstom, et. al.)

科罗纳多砂岩被置于古生代的石炭纪时期。在那里发现的化石是陆生化石：爬行动物、蜘蛛和蝎子的足迹。与下层相比，那里没有发现海洋化石。（Hill等，第13章）在这里发现了针叶状（非开花）树木的花粉。（Hill等，第14章）估计年龄为280 Myr。（Karlstom等）

Photo: NPS.gov

照片：NPS.gov

Hermit Formation

海里形成

With a projected age of about 285 Myr (Karlstom, et. al.) in Permian Period, this formation is made of soft, easily eroded shales which have formed a slope. Its softness has undermined the layers of sandstone and limestone above it and caused large blocks to fall to the lower parts of the canyon. It contains fossils of ferns, conifers and other plants, as well as fossilized tracks of reptiles and anphibians.

该地层的年龄约为285百万年（Karlstom等），属于石炭纪时期。该地层由软而易被侵蚀的页岩组成，形成了一个斜坡。其软性导致上层的砂岩和石灰岩层发生侵蚀，使大量岩块坠落到峡谷的下部。该地层中含有蕨类、裸子植物及其他植物的化石，以及爬行动物和两栖动物的化石足迹。

卡布 formation 被归入古生代的石炭纪。在那里发现的化石是海洋化石：海绵、珊瑚、双壳类、苔藓虫、软体动物、腕足类、头足类、鲨鱼和有骨鱼类。三叶虫也存在，但较少。(Hill等，第13章) 预估年龄为270百万年 (Hill等，Karlstom等)。托罗韦普 formation 被归入古生代的石炭纪。在那里发现的化石是海洋化石：海绵、珊瑚、双壳类、苔藓虫、软体动物、腕足类、头足类、鲨鱼和有骨鱼类。三叶虫也存在，但较少。(Hill等，第13章) 预估年龄为275百万年 (Karlstom等)。

Supai Group

苏帕伊组

The Supai Group is placed in the Paleozoic Era, Mississippian and Pennsylvanian Periods. The fossils there are marine fossils: brachiopods, gastropods, pelecypods,corals,bryozoans, conodonts, sharks. (Hill,et al.,Ch13) Fossil pollen from conifer-like (non-flowering) trees is found here. (Hill,et al.,Ch14) The projected age is 290-320 Myr (Karlstom, et. al.). This includes Esplanada Sandstone (290Myr), Wescogame Formation (300 Myr), Manakacha Formation (315 Myr), Watahomigi Formation 320 Myr)

Supai组属于古生代的密西西比期和石炭纪时期。该地的化石为海洋生物化石：双壳类、软体动物、腕足类、珊瑚、苔藓动物、三叶虫和鲨鱼。 (Hill等，第13章) 这里发现了针叶状（非被子植物）树木的花粉。 (Hill等，第14章) 预估年龄为290-320百万年 (Karlstom等)。这包括Esplanada砂岩（290百万年）、Wescogame组（300百万年）、Manakacha组（315百万年）、Watahomigi组（320百万年）。

Surprise Canyon Formation

惊奇峡谷岩层

Chinle组被归入中生代三叠纪时期，由色彩斑斓的泥岩和砂岩组成，风化后形成亚利桑那州Painted Desert和Petrified Forest国家公园中的低矮圆丘。这里保存的化石包括许多原始的针叶树和几个在下伏古生代岩石中未出现的植物群。还有昆虫、蝎子、淡水鱼以及多种四足动物的化石。早期恐龙的化石也有所发现。Hill等学者列出的化石包括淡水蛤蜊、蟹类、甲虫、肺鱼、拟鳄鱼、异齿龙和一种早期两足恐龙Coelophysis。在Chinle组中未发现任何海洋生物。Moenkopi组也归属于中生代三甸纪时期。该组发现的化石主要是陆生化石。发现包括大型两栖动物、足迹和拟鳄鱼鱼类。（Hill等，Ch13）

The Surprise Canyon Formation is placed in the Paleozoic Era, Mississippian and Pennsylvanian Periods. The fossils there are marine fossils: brachiopods, gastropods, pelecypods,corals,bryozoans, conodonts, sharks. (Hill,et al.,Ch13) Fossilized spores from lycopods and ferns are plentiful here and in layers above. In lower layers only the simple trilete (three-lobed) spores from now-extinct simple spore-bearing plants and algae were found.(Hill,et al.,Ch14) The projected age is 325 Myr (Karlstom, et. al.)

Redwall Limestone

红壁石灰岩

The Redwall Limestone is placed in the Paleozoic Era, Mississippian and Pennsylvanian Periods. The fossils there are marine fossils: brachiopods, gastropods, pelecypods,corals,bryozoans, conodonts, sharks. (Hill,et al.,Ch13) It forms sheer cliffs 400-500 ft high which are a barrier to travel to the bottom of the canyon. There are many caves and arches in the limestone. The projected age is 340 Myr.(Hill et. al., Karlstom, et. al.)

红崖石灰岩属于古生代的密西西比期和石炭纪。其中的化石是海洋生物：双壳类、软体动物、腕足类、珊瑚、苔藓动物、三叶虫和鲨鱼。（Hill等，第13章）该石灰岩形成高400-500英尺的陡峭峭壁，成为进入峡谷底部的障碍。石灰岩中有很多洞穴和拱门。其估计年龄为3.4亿年。（Hill等，Karlstom等）

Photo:nps.gov

Photo:nps.gov（矿物名）

Temple Butte Limestone

Temple Butte Limestone（矿物名）

Surprise Canyon Formation 属于 Paleozoic 时代，即 Mississippian 和 Pennsylvanian 时期。该地的化石为海洋生物化石：双壳类、软体动物、腕足类、珊瑚、苔藓动物、三叶虫和鲨鱼。（Hill 等，第13章）这里以及其上层富含煤蕨和蕨类的化石孢子。在下层仅发现来自现已灭绝的简单孢子植物和藻类的简单三室（三室的）孢子。（Hill 等，第14章）其估计年龄为 325 百万年（Karlstom 等）。

The Temple Butte Limestone is placed in the Paleozoic Era, Devonian Period. The fossils there are marine fossils: massive stromatoporoid sponges, rugose corals, tabulate corals, brachiopods, trilobites, placoderm fish, conodonts. (Hill,et al.,Ch13) The projected age is 385 Myr (Hill et. al., Karlstom, et. al.).

Frenchman Mountain Dolostone

法国山白云质岩

500 Myr (Karlstom, et. al.)

Muav Limestone

穆瓦石灰岩

Temple Butte Limestone 属于古生代的 Devonian 期。其中的化石为海洋生物化石：大型的石海绵、棘皮珊瑚、板珊瑚、双壳类、三叶虫、盔甲鱼、三叶虫。 (Hill,et al.,Ch13) 预估年龄为 385 百万年 (Hill et. al., Karlstom, et. al.). 500 百万年 (Karlstom, et. al.)

The Muav Limestone is placed in the Paleozoic Era, Cambrian Period. The fossils there are marine fossils: early trilobites,brachiopods,echinoderms, sponges. (Hill,et al.,Ch13) The projected age is 504 Myr.(Karlstom, et. al.)

Bright Angel Shale

Bright Angel Shale（矿物名）

穆阿夫石灰岩属于古生代寒武纪时期。其中的化石为海洋生物化石：早期三叶虫、腕足类、棘皮动物和海绵动物。（Hill等，第13章）其估算年龄为504百万年。（Karlstom等）

The Bright Angel Shale is placed in the Paleozoic Era, Cambrian Period. The fossils there are marine fossils: early trilobites,brachiopods,echinoderms, sponges. (Hill,et al.,Ch13)The projected age is 506 Myr. (Karlstom, et. al.)

Tapeats Sandstone

塔皮斯砂岩

The projected age is 508 Myr. (Karlstom, et. al.) This layer is composed of medium-grained and coarse-grained sandstone. Ripple marks are found in its upper layers, indicative of a sea environment. It contains fossils of trilobites and brachiopods, and trilobite trails are found there.

Sixtymile Formation

六十二英里岩层

510 Myr (Karlstom, et. al.)

Great Unconformity

大褶皱

Bright Angel Shale 属于古生代寒武纪时期。其中的化石为海洋生物化石：早期三叶虫、腕足类、棘皮动物和海绵动物。（Hill 等，第13章）其估计年龄为 506 百万年。（Karlstom 等）估计年龄为 508 百万年。（Karlstom 等）该层由中粒至粗粒砂岩组成。其上层有波痕，表明为海洋环境。其中含有三叶虫和腕足类化石，且有三叶虫的足迹。（Karlstom 等）510 百万年（Karlstom 等）

The term "unconformity" is used for a location where two layers of rock are in contact, but there is evidence that material is missing, i.e., the two layers were not formed at the same time. The "Great Unconformity" is perhaps the most famous unconformity. At some locations, the Tapeats Sandstone is in direct contact with the Vishnu Basement Rock where the time gap may be 1200 Myr.

Grand Canyon Supergroup

大峡谷群

"A thick group of rocks known as the Grand Canyon Supergroup was deposited on top of the schist and granite. Though the group includes several rock types, it is considered as a single unit that experienced a similar history following deposition."

一块被称为大峡谷群的厚层岩石沉积在片麻岩和花岗岩之上。尽管该群包含几种不同的岩石类型，但被认为是一个整体单位，其形成历史在沉积后基本相似。

The perspective for this illustration of the Supergroup was taken from Grand Canyon Explorer. The following descriptions are excerpted from that source.

Chuar Group: Projected age is from 825 to 1000 Myr. Includes the Sixty Mile Formation - a tan layer composed primarily of sandstone, but some shale sections. Also the Kwagunt Formation composed of shale, mudstone and some limestone. It contains some stromatolite fossils, perhaps the oldest fossils in the Grand Canyon. The Galeros Formaton contains interbedded sandstone, limestone and shale. There are also stromatolites in this layer.
Chuar 组：年龄估计为825至1000百万年。包括Sixty Mile组——主要由砂岩组成的一层，但也有部分页岩层。还有Kwagunt组，由页岩、泥岩和一些石灰岩组成。该组包含一些层状岩化石，可能是大峡谷中最古老的化石。Galeros组包含砂岩、石灰岩和页岩互层的层，该层中也有层状岩化石。
Nankoweap Formation: Age of about 1050 Myr, composed of coarse-grained sandstone. Not included in either the Chuar Group or the Unkar Group because it is bounded by unconformities on both sides.
南克韦普组：年龄约1050百万年，由粗粒砂岩组成。由于其两侧均被不整合面所界，因此不包括在楚尔组或恩卡尔组之中。
Unkar Group:
- Cardenas Lavas - dark brown layer of basaltic lava flows. Recent dating of this layer reports 1082 Myr (NPS Numeric Ages )
  卡德纳斯熔岩流 - 一种暗棕色的玄武岩熔岩流。该层的最新测年结果为1082百万年（NPS数字年龄）
- Dox Sandstone - Layer about 1120 Myr (NPS), sandstone interbedded with shale. Contains stromatolite and algae fossils.
  多克斯砂岩——约1120百万年（NPS）的层，与页岩交替沉积。含有蓝绿藻和藻类化石。
- Shinumo Quartzite - Layer about 1130 Myr (NPS), composed of sandstone.
  Shinumo Quartzite - 厚约1130百万年（NPS），由砂岩组成。
- Hakatai Shale - Layer about 1230 Myr (NPS), primarily shale with some sandstone. Its color is bright orange-red which gives Red Canyon its name.
  Hakatai Shale - 约1230百万年前的层系（NPS），主要为页岩，夹杂有砂岩。其颜色为鲜艳的橙红色，因此得名Red Canyon。
- Bass Formation - Layer about 1250 Myr, composed primarily of limestone with some interbedded shale. It contains stromatolite fossils. There is a volcanic ash layer at the base of the Bass Formation which has been dated using the Uranium-Lead method at 1255 +/- 2 Myr. It is interesting that in 1986 the magnetic field direction of iron minerals at this location was measured and compared with iron minerals in strata outside the Grand Canyon. The resulting date was 1250 Myr, in agreement with the radiometric age value. (Hill, et al Ch 9).
  Bass层形成于约1250百万年，主要由石灰岩组成，其中夹杂着一些页岩。该层含有叠层石化石。在Bass层底部有一个火山灰层，其年龄通过铀-铅法测定为1255±2百万年。有趣的是，1986年在此地测量了铁矿物的磁場方向，并与Grand Canyon外层的铁矿物进行了比较。所得结果为1250百万年，与放射性年龄值一致。(Hill等，第9章)。
Unkar Group:（矿物名）

这张超群组的示意图是从Grand Canyon Explorer拍摄的。以下描述摘自该来源。

The Grand Canyon Supergroup of formations shows no animal or multicellular fossils. It is placed in the late Proterozoic Era.

大峡谷群的岩石层中没有动物或多细胞生物的化石。它被归入晚元古代时期。

Another depiction of the Grand Canyon Supergroup from the opposite direction comes from the National Park Services article on numeric ages. This article is part of a series adapted from the Natural Resources Report "Telling Time at Grand Canyon: 2020 Update".

从相反方向描绘的大峡谷群另一幅图来自国家公园管理局关于数值年龄的文章。这篇文章是改编自自然资源报告《大峡谷：2020年更新》。

Vishnu Schist

Vishnu Schist（矿物名）

‘不整合’一词用于描述两个岩层接触的地方，但有证据表明中间缺失了某些材料，即这两个岩层并非在同一时间形成。‘大不整合’可能是最著名的不整合之一。在某些地点，塔皮斯砂岩直接与维苏威基岩接触，其中的时间间隔可能达到1200 Myr。

The precambrian rock that forms the "basement" for the grand staircase strata is generally called Vishnu Basement Rocks, which appear to be of volcanic origin and have been lifted from deeper locations in the time period between 1750 and 1660 Myr. Vishnu Schist is one component of the crystalline basement rock. Another component of basement rock is Elves Chasm Gneiss, which is thought to date to about 1840 Myr. It is in the form of igneous intrusions (called plutons) and contains iron and magnesium rich (mafic) materials. No fossils have been found in this basement rock. It is placed in the early Proterozoic Era. The projected age is 1700-1850 Myr.

Zoroaster Granite

佐拉斯特花岗岩

形成‘大台阶地层’基础的前寒武纪岩石通常被称为维斯努基础岩，这些岩石似乎具有火山起源，并在1750至1660百万年期间从更深处抬升而来。维斯努片岩是结晶基础岩的一个组成部分。基础岩的另一个组成部分是埃夫斯裂谷片麻岩，其年代估计约为1840百万年。它以火成侵入体（称为岩体）的形式存在，含有富含铁和镁（基性）的材料。在这些基础岩中未发现化石。它被归类于早太古代时期。其估计年龄为1700-1850百万年。

Zoroaster Granite intruded into the Vishnu Schist at the base of the Grand Canyon. The Zoroaster Granite has a characteristic age of 1740 Myr.

佐罗斯特花岗岩侵入了大峡谷底部的维施努片岩。佐罗斯特花岗岩具有1740百万年（Myr）的特征年龄。

A list of the Vishnu Basement Rocks with numeric ages may be found in the National Park Service publication Numeric Ages of Grand Canyon Rocks.

Examples of sedimentary rock

沉积岩的例子

Geological time scale

地质时间尺度

大峡谷岩石的数值年龄列表可参见国家公园管理局出版的《大峡谷岩石的数值年龄》。

Index

References:

Geophysics

Karlstrom, Crossey, Mathis and Bowman, Telling Time at Grand Canyon National Park

Hill, C., et al.
The Grand Canyon, Ch 3

Lutgens and Tarbuck
Ch 6

Grand Canyon Explorer

索引参考：地球物理学 Karlstrom, Crossey, Mathis 和 Bowman，Grand Canyon National Park 的时间测定 Hill, C. 等，《大峡谷》第3章 Lutgens 和 Tarbuck 第6章 Grand Canyon Explorer

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