![]() ![]() Īs one of Steno's Laws, the principle of original horizontality served well in the nascent days of geological science. Picture from Glen Canyon National Recreation Area, Utah.įrom these observations is derived the conclusion that the Earth has not been static and that great forces have been at work over long periods of time, further leading to the conclusions of the science of plate tectonics that movement and collisions of large plates of the Earth's crust is the cause of folded strata. From top to bottom: Rounded tan domes of the Navajo Sandstone, layered red Kayenta Formation, cliff-forming, vertically jointed, red Wingate Sandstone, slope-forming, purplish Chinle Formation, layered, lighter-red Moenkopi Formation, and white, layered Cutler Formation sandstone. These strata make up much of the famous prominent rock formations in widely spaced protected areas such as Capitol Reef National Park and Canyonlands National Park. Igneous intrusions that “cut across” or enter other rocks are younger than the rocks they cross.The Permian through Jurassic stratigraphy of the Colorado Plateau area of southeastern Utah is a great example of Original Horizontality. Lateral Continuity (Lateral means “side to side”) Principle of inclusions That which is included is _ (older? Younger?)Ģ7 7. Law of Inclusions Rock particles/fragments that are found in rock layers are older than the rock layer it is found in.Ģ6 Principle of inclusions That which is included is _ (older When different fossils are found in the same layer, they existed during the same time period.Ģ5 6. The fault is younger than the beds.įossils of different Plants and Animals are found in sedimentary rock layers. Templin Highway, Castaic, California A small fault displaces tilted beds. North shore of Lake Superior, Ontario Canada A dark-colored dike has intruded into older light colored granite. Intrusion - igneous rock that forms when magma squeezes between existing rock and hardens Intrusion - igneous rock that forms when magma squeezes between existing rock and hardensĮxample of Cross-cutting (extrusive) Examples of Cross-Cutting Extrusion - igneous rock that forms when lava flows on Earth’s surface and hardensġ9 Principle of Cross-Cutting Relationships James Hutton ( An igneous intrusion or a fault event must be younger than the rocks it intrudes or cuts across Igneous intrusions/extrusions that “cut across” or enter other rocks are younger than the rocks they crossĪny feature that cuts across a rock or layer of sediment is younger than the rock or layer it cuts youngest layer Intrusion: Occurs when magma squeezes between layers of pre-existing rock beneath the Earth’s surface -Causes surrounding layers to metamorphose (Contact metamorphism) When molten rock flows on the Earth’s surface forming an igneous rockġ3 -Causes surrounding layers to metamorphose (Contact metamorphism) In undisturbed sedimentary rock or lava flows In undisturbed sedimentary rock or lava flows: Top = youngest layer Bottom = oldest layerġ0 Unconformity Gaps or missing layers in the rock record due to erosion SUPERPOSITION -The bottom layer of horizontal sedimentary rock layers is always the oldest, UNLESS the layers have been overturned or have had older rock formed on top of it *The lower layers must first be in place before the next layer can be depositedħ LAW OF SUPERPOSITION For undisturbed rocks, the oldest layer is on the bottom and the youngest is on top Supai is oldest – WHY?ĩ Law of Superposition Top = youngest layer Sedimentary rocks form in horizontal layers parallel to Earth’s surface and will remain that way unless disturbed SILT SAND CLAY SILT CLAY EARTH'S SURFACEĥ 3. Sedimentary rock layers are ALWAYS laid down in horizontal layers, until some other process alters them The processes that shape the Earth today are the same processes that occurred in the geologic past “The present is the key to the past” ![]() UNIFORMITARIANISM:"- Presentation transcript:ġ SEVEN PRINCIPLES Of GEOLOGY 1. Presentation on theme: "SEVEN PRINCIPLES Of GEOLOGY 1. ![]()
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