Sedimentary rock Middle Triassic marginal marine sequence of siltstones (below) and limestones (above), Virgin Formation, southwestern Utah, USA Genetic classification Based on the processes responsible for their formation, sedimentary rocks can be subdivided into four groups: clastic sedimentary rocks, biochemical (or biogenic) sedimentary rocks, chemical sedimentary rocks and a fourth category for "other" sedimentary rocks formed by impacts, volcanism, and other minor processes. Clastic sedimentary rocks Main article: Clastic rock Clastic sedimentary rocks are composed of silicate minerals and rock fragments that were transported by moving fluids (as bed load, suspended load, or by sediment gravity flows) and were deposited when these fluids came to rest. Conglomerates and breccias Sandstones Composition of framework grains The relative abundance of sand-sized framework grains determines the first word in a sandstone name. Abundance of muddy matrix between sand grains Mudrocks Biochemical sedimentary rocks
Geologic time scale Online exhibits Geologic time scale Take a journey back through the history of the Earth — jump to a specific time period using the time scale below and examine ancient life, climates, and geography. You might wish to start in the Cenozoic Era (65.5 million years ago to the present) and work back through time, or start with Hadean time (4.6 to 4 billion years ago)* and journey forward to the present day — it's your choice. Ways to begin your exploration: Use the links in the "time machine" below and explore a specific period that interests you.Read more about the geologic time scale, its origins and its time divisions.Find out more about plate tectonics, an important geological concept in any time period!
Capture List of tectonic plates Plate tectonics map from NASA Current plates[edit] Geologists generally agree that the following tectonic plates currently exist on the Earth's surface with roughly definable boundaries. Tectonic plates are sometimes subdivided into three fairly arbitrary categories: major (or primary) plates, minor (or secondary) plates, and microplates (or tertiary plates). Major plates[edit] These seven plates comprise the bulk of the continents and the Pacific Ocean. Pacific Plate – 103,300,000 km2North American Plate – 75,900,000 km2Eurasian Plate – 67,800,000 km2African Plate – 61,300,000 km2Antarctic Plate – 60,900,000 km2Indo-Australian Plate – 58,000,000 km2 Often considered two plates: Australian Plate – 47,000,000 km2Indian Plate – 11,900,000 km2South American Plate – 43,600,000 km2 Minor plates[edit] These smaller plates are often not shown on major plate maps, as the majority do not comprise significant land area. Microplates[edit] Ancient continental formations[edit] Ancient supercontinents[edit]
Hadean: Overview The name Hadean Eon comes from Hades, the underworld of Greek mythology. It refers to the “hellish” conditions of the Earth during the earliest part of its history, when much of the Earth’s surface remained molten. The Hadean Eon of geologic time began with the birth of the solar system, including our planet, Earth, and ended with the formation of the oldest rocks that are still preserved on the surface of Earth. The Hadean is the first period in Earth history, but one for which we have little record. The Earth began to form about 4.6 billion years ago through the condensation of material around the sun. As this material collected, further cosmic material was drawn to it by gravity from all directions, increasing the size of the Earth.
Earth Systems - 6th Grade Science Earth Systems, Structures and Processes6.E.2 Understand the structure of the earth and how interactions of constructive and destructive forces have resulted in changes in the surface of the Earth over time and the effects of the lithosphere on humans. 6.E.2.1 Summarize the structure of the earth, including the layers, the mantle and core based on the relative position, composition and density. 6.E.2.2 Explain how crustal plates and ocean basins are formed, move and interact using earthquakes, heat flow and volcanoes to reflect forces within the earth. 6.E.2.3 Explain how the formation of soil is related to the parent rock type and the environment in which it develops. 6.E.2.4 Conclude that the good health of humans requires: monitoring the lithosphere, maintaining soil quality and stewardship. *** Please wait while the videos load. *** 6.E.2.1 - Layers of the Earth 6.E.2.3 - Geology Kitchen #1 - What is a Mineral? 6.E.2.3 - Geology Kitchen #2 - Identifying Minerals
The 10 Best STEM Resources By Phil Nast, retired middle school teacher and freelance writer Found In: mathematics, science, preK-2, 3-5, 6-8, 9-12 Curriculum Resources Exploratorium Provides interactives, web features, activities, programs, and events for K-12. Saturday and Summer professional development workshops are available through the Teacher Institute. NASA – For Educators Lesson plans, teacher guides, classroom activities, video clips, games, posters, and more for teachers and students in grades K-4, 5-8, 9-12, and higher education. Professional Development STEM Education Resource Center Provides nearly 4,000 science, technology, engineering and math resources for PreK-5, 6-12 as well as free, self-paced modules for teachers teaching global climate change to middle school and high school students.