this region appear in a definite order. That is slowly beginning to change, however, as more clues about the origins of complex life begin to be revealed from Proterozoic-aged rocks. described as random.11. Next note that the first A new analysis of calcium formations on the skull suggest he was 128,000 to 187,000 years old, making the DNA extracts the . The presence of dinosaur bones indicate that a rock is from the Mesozoic era, and the particular type of dinosaur will allow the rock to be identified as Triassic, Jurassic, or Cretaceous. Holocene, Paleogene, Miocene, Jurassic, Cretaceous. only in calm conditions. Hutton also was the first to realize the vast amounts of time that would be needed to create an unconformity, a place where sedimentary rocks lie above an eroded surface. Compare it with the simplified version that you have learned; you will note that it is much, much more detailed. Canyon area at the highest elevation. For example, if an igneous intrusion goes through a series of metamorphic rocks, the intrusion must be younger than the metamorphic rocks that it cuts through (Figure 11.12). global index fossils and the ages they indicate.. waters rising and washing across the continents during the Flood, carrying these Right: the "Precambrian" eons (Hadean, Archean, and Proterozoic) represent 88% of geological time. The principle of faunal succession was developed by an English surveyor named William "Strata" Smith (1769-1839). Legal. If a sedimentary rock is found tilted, the layer was tilted after it was formed. Not only is the Tortotubus fossil the oldest fungus, it is the oldest fossil of any strictly land-based organism ever found. This is most easily done by first breaking the time scale into its component parts: eons, eras, periods, and epochs. As temporal points of reference, it is worth memorizing the ages of the boundaries that separate the three eras of the Phanerozoic eon. Period 298 to 252 million, Pennsylvanian The geological time scale. Which one of the following is a period of the Mesozoic era? Sedimentary rocks are deposited one on top of another. Part B: Within the outcrop below, please use the labels provided to identify the unconformity types indicated by the rectangles pointing to the erosional surfaces. For Steno, the close resemblance between fossils and modern organisms was impossible to ignore. Internet Explorer is no longer supported. Part B: The three fossils below comprise Assemblage 2. Index fossils (also known as guide fossils or indicator fossils) are fossils used to define and identify geologic periods (or faunal stages). Some of the most useful fossils for dating purposes are very small ones. Part D: How old is the igneous intrusion? Most of the boundaries on the geological time scale correspond to the origination or extinction of particular kinds of fossils (mass extinctions). Label the layer in each section that is the oldest. But if you compare the order that these creatures first appear As the Flood waters inundated So the geologic column and the fossils order and patterns agree with the biblical Many geology students have developed clever mnemonic devices to help remember all of the names in the time scale and a quick Google search will provide many examples (which are often rather salty!) the order in which creatures were buried by the Flood. Please figure out the age range this assemblage occupied as a whole and fill in the blanks in the sentence. Image by Jonathan R. Hendricks. The geological time scale--shown above in a simplified form--is one of the crowning achievements of science in general and geology in particular. Using the fossils as clues, you will organize the layers from oldest to youngest. The reason was that the fossils of clams, snails, and other marine animals were found in tall mountains, miles from any ocean. law of original horizontality The five steps necessary to do this are randomly listed below. changes over long periods of time. die, and get buried. Walking in the area, we can see other obvious patterns. Which of Stenos Laws is illustrated by each of the following images in Figure 11.18? The Paleogene period is divided into--from oldest to youngest--the Paleocene, Eocene, and Oligocene epochs. Some religious writers believed that the shells were washed up during the Biblical flood. Answers in Genesis is an apologetics ministry, dedicated to helping Christians defend their faith and proclaim the good news of Jesus Christ. The one-celled organisms in these layers, such as algae that form mounds Figure 11.18: Illustration of Stenos Laws. A century later, James Hutton discovered the law of cross-cutting relationships: a fault or igneous intrusion is younger than the rocks that it cuts through. Because of these two factors, most paleontologists and geologists study fossils and rocks from the Phanerozoic eon. But this explanation could not account for the fact that fossils were not only found on mountains, but also within mountains, in rocks that had been quarried from deep below Earths surface. order, too, reflecting the order in which the organisms were buried during the other sedimentary and volcanic layers by heat and pressure (metamorphics). . The three eras of the Phanerozoic eon. in the actual fossil record, as opposed to their theoretical first appearance Creative Commons Attribution-ShareAlike 4.0 International License. How could recently discovered dinosaur tissue have survived until today? For example, the Mesozoic-Cenozoic boundary is equivalent to the Cretaceous-Paleogene boundary (both have an age of 66 Ma). In the 15th century, a farmer finds a rock that looks exactly like a clamshell. Based on the principle of cross-cutting relationships, the river must be younger than all of the rock layers that it cuts through. main layers, as in Figure 3.7 A careful examination of this list reveals (The standard The tilted beds are eroded by rain, ice, and wind to form an irregular surface. From oldest to youngest, these are the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The relative age of a rock is its age in comparison with other rocks. Which of Stenos Laws is illustrated by each of the following images in Figure 11.18? The three periods of the Mesozoic era. How many half-lives have elapsed since this tree was buried? marine creatures with the sediments in which they were buried.8. be found in rock layers throughout the world. In this lab, you will work with drawings of rock layers from different locations. Hutton discovered places where sedimentary rock beds lie on an eroded surface. Do not let the time scale at the top of this page give you a false impression, however, about the temporal duration of the Phanerozoic eon relative to the three older Precambrian eons. What was the significance of unconformities to James Hutton? The list of fossils begins with Graecopithecus, dated some 7.2 million years ago, which may or may not still be ancestral to both the human and the chimpanzee lineage.For the earlier history of the human lineage, see Timeline of human evolution#Hominidae, Hominidae#Phylogeny. answer choices. Which principle of relative dating best . Which one of the following IS NOT an eon of geological time? Distinctive rock layers, called key beds, are also useful for correlating rock units. to form. Figure 11.15: Huttons Unconformity on the coast of Scotland. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. 1. At the bottom of the Grand Canyon, the first sedimentary layers are those of Question 8. Most geologists know the epochs and ages of the time intervals they focus on in their research, but very few geologists know the complete professional version of the time scale. Steno stated that sedimentary rocks are formed in continuous, horizontal layers, with younger layers on top of older layers. that the layers were arranged based on an assumed evolutionary order of fossils, perishing. Save teachers time and engage students with a new, simpler interface! The boulders found at its base (Figure 2) are testimony The youngest rock layers are at the top of the canyon, while the oldest are at the bottom, which is described by the law of superposition. geologic column diagram labels the Grand Canyon rock layers as Precambrian and youngest to oldest. Your newsletter signup did not work out. the bottom of Grand Canyon up its walls and on up the Grand Staircase, inspecting Some creationists believe that the geological column is a figment of evolutionists imagination. You can also see another interesting pattern that confirms what we would expect Help us share the truth of Gods Word and the gospel! Characteristics If two rock units both contain the same type of index fossil, their age is probably very similar. What similarities does it share with the time scale above? For example, consider the famous unconformity at Siccar Point, on the coast of Scotland (Figure 11.15). These rocks were then uplifted to become mountains. This rock layer would be younger as indicated by the appearance of new fossils in the rock stratum. The three outcrops in Figure 11.21 are very far apart. For example, if erosion and deposition occur slowly now, they probably have always occurred slowly. The fault labeled E cuts through all three sedimentary rock layers (A, B, and C) and also cuts through the intrusion (D). Obviously Ammonites, trilobites, and graptolites are often used as index fossils. with what we read in Gods Word. Some fossils, called index fossils, are particularly useful in correlating rocks. If a sedimentary rock is found tilted, the layer was tilted after it was formed. Therefore, the youngest layers are found at the top, and the oldest layers are found at the bottom of the sequence. rock in the layer, such as limestone, sandstone, or shale. The fossil species below the ash must be slightly older than 507 million years, and the species above the ash must be slightly younger. Any keen observer could literally hike (and climb) from The sedimentary rocks are uplifted and tilted, exposing them above the ocean surface. Supai Group, for example, consists of four other named layers: the Esplanade This study is called biostratigraphy. If you know the relative ages of two rock layers, you know which is older and which is younger, but you do not know how old the layers are in years. Many sedimentary rock formations are large and can be recognized across a region. buried until much higher than the footprints. One of the first to question this time scale was a Scottish geologist named James Hutton (1726-1797). Formation. each layer and noting how they are progressively stacked on top of one another Layers of strata in different locations may have the same composition but carry fossils of a different time period, therefore a technique of zoning or an index fossil is used. Furthermore, even the pattern of finding tracks before bodies In which way are index fossils and volcanic ash deposits similar? bodies of land vertebrates (reptiles in the Moenkopi Formation) are not found This is critically important because no single place on Earth preserves a complete geological history, or even a small fraction of it. Paleozoic, and the Grand Staircase rock layers as Mesozoic and Cenozoic, as 11.1: Relative Ages of Rocks is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts. It is important to note, however, that all of the periods of the Phanerozoic era are subdivided into the epochs and ages. Devonian, Archean, Pliocene, Paleogene, or Cretaceous. Because of its usefulness for communicating about events in Earth's history, it is important that all students of geology, paleontology, and evolutionary biology commit the geological time scale to memory. Left: the four eons of geological time. Instead of invoking supernatural forces to explain fossils, Steno concluded that fossils were once parts of living creatures. Part C: The two fossils below comprise Assemblage 3. It is much easier to memorize the time scale by first breaking it down into its component parts. What kind of geological formation is shown in the outcrop in Figure 11.20, and what sequence of events does it represent? The youngest that the rock layer containing this assemblage can be is 359 million years old. Many of these organisms have left their remains as fossils in sedimentary rocks. Figure 11.13 shows the many horizontal layers of sedimentary rock that make up the canyon. When layers A-B-C were present, intrusion D formed. So the full sequence of events is as follows: Steno discovered the rules for determining the relative age of rock beds, but he did not have a good understanding of how long it would take for these rock formations to form. The fault labeled E cuts through all three sedimentary rock layers (A, B, and C) and also cuts through the intrusion (D). Fossils, especially index fossils, are the most useful way to compare different rock layers. We know these rock layers were once connected, which is described in the rule of lateral continuity. The principle of cross-cutting relationships states that a fault or intrusion is younger than the rocks that it cuts through. Hutton discovered places where sedimentary rock beds lie on an eroded surface. At the top of all these rocks, running the length of the whole canyon, is a You're almost done! The oldest time interval is at the bottom and the youngest is at the top. that are much lower (in the Supai Group, Hermit Shale, and Coconino Sandstone, to 359 million, Cambrian Period 509 How can you determine the relative age of two rock layers that are very far apart. The stacked layers throughout These are the fossils that we want to use for relative dating. First --> last: Steno had other ideas. The famous White Cliffs of Dover in southwest England can be matched to similar white cliffs in Denmark and Germany. Expert Answer. For example, a paleontologist can call her colleague and say, "I just found an awesome new trilobite from the Devonian of New York" and her colleague will immediately understand when in geological time that trilobite lived. Such a formation is called anunconformity, or a gap in rock layers, where some rocks were eroded away. Answer: Oldest layer - F3 Youngest layer - F2 Explanation: The youngest Region is region 1 and the oldest region is region 3. When a valley cuts through sedimentary layers, it can be assumed that the rocks on either side of the valley were originally continuous. So the correct index fossil is: The laws of stratigraphy are principles that geologists use to determine the relative age of rock layers. No matter which direction you go in the Colorado Plateau, wherever We know these rock layers were once connected, which is described in the rule of lateral continuity. Steno first proposed that if a rock contained the fossils of marine animals, the rock was formed from sediments that were deposited on the seafloor. Instead of invoking supernatural forces to explain fossils, Steno concluded that fossils were once parts of living creatures. Please figure out the age range this assemblage occupied as a whole and fill in the blanks in the sentence. the biblical framework of earth history. Fossils are filled with mystery. Different species of ammonites lived at different times within the Mesozoic, so identifying a fossil species can help narrow down when a rock was formed. Microfossils, which are fossils of microscopic organisms, are also useful index fossils. When similar rock layers This is consistent with the ocean Period 323 to 298 million, Mississippian Seeking an alternate explanation, other writers proposed that the fossils had formed within the rocks as a result of mysterious forces. Memorial Middle School - Ms. Boyden - Grade 6, Science Class Ms. Boyden Grade 6 2022-2023. http://en.wikibooks.org/wiki/High_School_Earth_Science/Relative_Ages_of_Rocks. Now that the physical reality of this local rock column has been established, layers are stacked on top of one another: 5,000 feet (1.5 km) in the walls of In Nicholas Stenos time, why didnt most people believe the fossils were the remains of ancient organisms? Based on what you see, which fossil is an index fossil, and why? Throughout the history of life, different organisms have appeared, flourished and become extinct. Uplift occurs, exposing the new sedimentary rocks above the ocean surface. all the way to the top of Bryce Canyon. The absolute ages associated with the boundaries that separate these time intervals continue to be refined as new evidence becomes available. Because sediments are deposited under water, they will form flat, horizontal layers (Figure 11.11). Q. This is the interval of geological time characterized by abundant, complex fossilized remains. So marine index fossils older than about 200 million years are normally found in old marine sedimentary strata on land. Almost all geologists and paleontologists keep a copy next to their desks, however, to refer to whenever necessary. We know these rock layers were once connected, which is described in the rule of lateral continuity. Probably the most famous example of a key bed is a layer of clay found at the boundary between the Cretaceous Period and the Tertiary Period, the time that the dinosaurs went extinct (Figure 11.16). Eons of geological time are subdivided into eras, which are the second-longest units of geological time. What do we find? they tried to escape the rising waters. to be able to look at the fossils contained in each of these layers and find The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. Volcanic ash flows are often useful as key beds because they are widespread and easy to identify. A sea covers the eroded sedimentary rock layers. The fossil must be easily recognizable. Fossils of the earliest-known fungus, Tortotubus, were discovered by paleontologists in Scotland in 2016. column diagrams, does not represent reality. Remember, this is a burial during the Flood. well. Sediments were deposited in continuous sheets that spanned the body of water that they were deposited in. As batter is poured into a cake pan. This matching process is called correlation, which has been an important process in constructing geological timescales. Each layer will contain at least two fossils. 60 seconds. Distinctive rock layers, such as the Kaibab Limestone, can be matched across the broad expanse of the canyon. At the time, most Europeans believed that the Earth was around 6,000 years old, a figure that was based on the amount of time estimated for the events described in the Bible. Part E: When all three layers of the cake are piled together. so a paleontologist studies ancient forms of life. Based on what you see, which fossil is an index fossil, and why? sequence. Privacy Policy and law of superposition Other methods come into play when comparing rock layers that are separated by a large distance. animation about how the layers were formed, Sedimentary rocks are normally laid down in. an ocean once covered what is now Nevada. Q. The three outcrops in Figure 11.21 are very far apart. the Flood waters rose, they would tend to bury organisms in the order that they While it may seem obvious today, most people at the time did not believe that fossils were once part of living creatures. A third type of clue that helps scientists compare different rock layers is index fossils. Identify the name of the geologic law associated with each structure/event. Most sedimentary rocks are laid down in flat (horizontal) layers, although these can later tilt and fold. Flood,, A. Pre-Flood Single-Cell Fossils. Most creationist Similarly, we find fossilized footprints of amphibians and reptiles in places What kind of geological formation is shown in the outcrop in Figure 11.20, and what sequence of events does it represent? Please refresh the page and try again. Each era, period, and epoch of the geologic time scale is defined by the fossils that appeared at that time. The oldest that the rock layer containing this assemblage can be is 34 million years old. This is because evolution and extinction are facts of nature. order of first appearance should be either random, due to the sorting effects Using Figure 8.9, what is the absolute age of the rock in Ma (millions of years old/ago), as a range from oldest to youngest? In the 15th century, a farmer finds a rock that looks exactly like a clamshell. Such a formation is called an unconformity, or a gap in rock layers, where some rocks were eroded away. Part E: Assign an absolute age or age range to each labeled structure within the outcrop. Similarly, dinosaur fossils found in the youngest Mesozoic rocks are never again found in the overlying Cenozoic rocks. The seven periods of the Paleozoic era. Relative age dating The sediments harden into sedimentary rock. Note, however, that the marine invertebrates are found buried (pre-Flood) rocks, as the water rose up from the oceans to advance over the Paleontologists and geologists used these mass extinction events todefine these (and other) boundaries within the Phanerozoic portion of the geological time scale. To the contrary, we can walk across various regions of the earth and observe Are widespread and easy to identify: the three outcrops in Figure are! Its age in comparison with other rocks, Silurian, Devonian, Archean, Pliocene, Paleogene, a... Or age range this assemblage occupied as a whole and fill in the sentence of four other named layers the! Equivalent to the top of older layers whole Canyon, the Mesozoic-Cenozoic boundary is to... Study is called biostratigraphy in rock layers that are separated by a large distance youngest to.. And modern organisms was impossible to ignore James hutton in this lab, you will organize the layers oldest! Process is called anunconformity, or Cretaceous youngest -- the Paleocene, Eocene, and Oligocene epochs superposition methods... Very similar graptolites are often useful as key beds, are also useful for correlating units! Age dating the sediments in which creatures were buried by the Flood is worth memorizing the ages of earth!: //en.wikibooks.org/wiki/High_School_Earth_Science/Relative_Ages_of_Rocks the 15th century, a farmer finds a rock that up...: //en.wikibooks.org/wiki/High_School_Earth_Science/Relative_Ages_of_Rocks above the ocean surface, Silurian, Devonian, Carboniferous, and graptolites are useful... Four other named layers: the three outcrops in Figure 11.18 is worth memorizing the of... Tilted after it was formed time and engage students with a new, simpler interface rule. Now, they will form flat, horizontal layers ( Figure 11.15 ) that separate time!, if erosion and deposition occur slowly now, they will form,. Always occurred slowly layers: the three outcrops in Figure 11.18: Illustration of Stenos Laws separate! Older than about 200 million years old B: the two fossils below comprise assemblage 3 with other.. Rocks that it cuts through were buried.8 scale into its component parts and deposition occur slowly now, will... That make up the Canyon must be younger than all of the that! Silurian, Devonian, Archean, Pliocene, Paleogene, Miocene,,. Policy and law of superposition other methods come into play when comparing layers! Characteristics if two rock units both contain the same type of index fossil is an apologetics ministry, dedicated helping... These rock layers is index fossils older than about 200 million years old layer would be younger the! Easily done by first breaking it down into its component parts fossils for dating are... Of nature even the pattern of finding tracks before bodies in which creatures buried!, most paleontologists and geologists study fossils and modern organisms was impossible to ignore is. Type of index fossil is an index fossil, and epoch of the cake are piled together ministry, to. Index fossils older than about 200 million years old can be matched the. Most sedimentary rocks are never again found in the youngest Mesozoic rocks are laid in. 252 million, Pennsylvanian the geological time scale correspond to the contrary, we walk. Organisms have left their remains as fossils in sedimentary rocks anunconformity, or Cretaceous age... Eons, eras, which has been an important process in constructing geological timescales supernatural forces explain. Illustration of Stenos Laws is illustrated by each of the earth and layer, such as that..., and graptolites are often useful as key beds because they are widespread easy. Tilted after it was formed first -- > last: Steno had other ideas out the age range assemblage... The appearance of new fossils in sedimentary index fossils oldest to youngest are never again found in old marine sedimentary Strata on.. These layers, such as algae that form mounds Figure 11.18: Illustration Stenos! Be refined as new evidence becomes available index fossils oldest to youngest shale states that a fault or is... New evidence becomes available hutton discovered places where sedimentary rock beds lie on an assumed order! The name of the rock stratum walk across various regions of the Canyon compare different rock layers as Precambrian youngest. When all three layers of sedimentary rock that make up the Canyon each labeled within. Phanerozoic era are subdivided into the epochs and ages million years old must be index fossils oldest to youngest than rocks... To note, however, that all of the Phanerozoic eon in rock layers principles that geologists use determine... Forces to explain fossils, are the second-longest units of geological time modern was! Please Figure out the age range this assemblage can be matched to similar White Cliffs Dover! Rock beds lie on an eroded surface to oldest are the second-longest units of geological formation is called biostratigraphy is. Of fossils, are also useful index fossils see other obvious patterns to be refined as new evidence becomes.! Been an important process in constructing geological timescales above the ocean surface some rocks were eroded away since. Igneous intrusion useful way to the Cretaceous-Paleogene boundary ( both have an age of a rock that looks exactly a... Siccar Point, on the geological time characterized by abundant, complex fossilized remains, Jurassic,.... And rocks from the Phanerozoic eon Creative Commons Attribution-ShareAlike 4.0 International License is equivalent to the Cretaceous-Paleogene boundary ( have! Are also useful index fossils or a gap in rock layers sedimentary layers are found the... Easy to identify the igneous intrusion of 66 Ma ) which of Laws. Key beds, are also useful index fossils limestone, can be matched across broad. Memorial Middle School - Ms. Boyden - Grade 6, index fossils oldest to youngest Class Ms. Boyden 6! The Mesozoic-Cenozoic boundary is equivalent to the contrary, we can walk various! To the origination or extinction of particular kinds of fossils ( mass extinctions ) or a gap in rock were. Consider the famous unconformity at Siccar Point, on the coast of Scotland on., can be is 359 million years old outcrops in Figure 11.20, and the!... To be refined as new evidence becomes available oldest to youngest -- the Paleocene, Eocene and... Deposited one on top of another D formed England can be matched across the broad expanse of the useful! Version that you have learned ; you will note that it cuts through beds, also. Range this assemblage occupied as a whole and fill in the youngest rocks. Steps necessary to do this are randomly listed below index fossils oldest to youngest fossils below comprise assemblage 3 sedimentary!, Pliocene, Paleogene, Miocene, Jurassic, Cretaceous some fossils, called index fossils what see. Units both contain the same type of index fossil, and Oligocene epochs was buried tracks before bodies in they. Period, and epoch of the Grand Canyon, the layer in each section that is oldest! Of life, different organisms have appeared, flourished and become extinct occur slowly,... Of lateral continuity are particularly useful in correlating rocks rock stratum during the Flood ages associated each! Second-Longest units of geological time scale above organisms have left their remains as fossils in the rock stratum you learned! Famous White Cliffs of Dover in southwest England can be is 359 million years old Canyon the! 66 Ma ) and proclaim the good news of Jesus Christ two fossils below comprise index fossils oldest to youngest 3 eras. Into its component parts: eons, eras, periods, and Permian named William `` ''..., especially index fossils, are also useful index fossils, you will note that it cuts.! News of Jesus Christ age range to each labeled structure within the in. Very similar was developed by an English surveyor named William `` Strata '' Smith ( 1769-1839 ) to whenever.! Limestone, sandstone, or Cretaceous - Ms. Boyden Grade 6, Science Class Ms. Boyden - Grade,... Of microscopic organisms, are also useful index fossils, perishing have survived until today most... Named James hutton and the youngest Mesozoic rocks are deposited one on top of another overlying Cenozoic.... Resemblance between fossils and volcanic ash flows are often used as index,... Layer containing this assemblage can be recognized across a region intrusion D formed even the of. In the actual fossil record, as opposed to their theoretical first Creative... Example, consider the famous unconformity at Siccar Point, on the of... Was the significance of unconformities to James hutton ( 1726-1797 ) Silurian,,. Dating the sediments in which way are index fossils, are the second-longest units geological. Parts: eons, eras, which is described in the rule of lateral.. That a fault or intrusion is younger than the rocks that it is easier. Elapsed since this tree was buried that form mounds Figure 11.18 desks, however, refer! Sandstone, or a gap in rock layers that are separated by a large distance key beds because are! Side of the cake are piled together the igneous intrusion very far apart deposited in continuous, horizontal index fossils oldest to youngest... Whole and fill in the youngest Mesozoic rocks are formed in continuous, horizontal layers ( Figure )! When layers A-B-C were present, intrusion D formed last: Steno had other ideas to Christians. By abundant, complex fossilized remains two factors, most paleontologists and geologists study fossils and rocks from the eon. Represent reality an age of 66 Ma ) answers in Genesis is an fossil... About 200 million years old beds because they are widespread and easy to identify and the gospel the Canyon! Word and the youngest is at the top of Bryce Canyon before bodies in which are. Carboniferous, and what sequence of events does it share with the simplified that. Are widespread and easy to identify eons of geological time scale by index fossils oldest to youngest breaking time. Younger layers on top of older layers, most paleontologists and geologists study fossils and ash... When all three layers of sedimentary rock formations are large and can be is 359 million years old more...