on April 1, 2022
What is relative age mean?
GeologyRelative age is the age of a rock layer (or the fossils it contains) compared to other layers. It can be determined by looking at the position of rock layers. Absolute age is the numeric age of a layer of rocks or fossils. Absolute age can be determined by using radiometric dating. Which is an
on April 1, 2022
How long did Mt St Helens erupt?
GeologySummary of Events A wave of decreasing pressure down the volcanic conduit to the subsurface magma reservoir, which then began to rise, form bubbles (degas), and erupt explosively, driving a 9-hour long Plinian eruption. Steam-blast eruption from summit crater of Mount St. Helens. How long did Mount St. Helens erupt in 1980? Forty years ago,
on April 1, 2022
Where are mafic rocks commonly found?
GeologyINTRODUCTION. Mafic rocks that constitute the igneous oceanic crust are created at mid-ocean ridge seafloor spreading centers as a byproduct of partial melt from upwelling mantle. Where are mafic magmas most likely to be found? Mafic magmas are usually produced at spreading centers, and represent material which is newly differentiated from the upper mantle. Common
on April 1, 2022
Did Pennsylvania just have an earthquake?
GeologyThere were no significant confirmed earthquakes in or near Pennsylvania in the past 24 hours. When was the last earthquake in PA? Earthquake Catalog Date and time Mag Depth Location Aug 25, 2020 09:22 GMT 2.0 3.7 km Crawford County, Pennsylvania, 12 mi west of Meadville, USA Monday, June 1, 2020 GMT (1 quake) Jun
on April 1, 2022
Is Mesa a landform?
GeologyA mesa is a flat-topped mountain or hill. It is a wide, flat, elevated landform with steep sides. Mesa is a Spanish word that means table. Spanish explorers of the American southwest, where many mesas are found, used the word because the tops of mesas look like the tops of tables. What are the landforms?
on April 1, 2022
What is the Moho composed of?
GeologyThe Moho or Mohorovicic Discontinuity is a boundary that separates the crust from the upper mantle. The crustal rock above and the mantle rock below are different rocks based on silicate minerals. Is the Moho solid or liquid? The “Moho”, as it is often called for brevity, is the boundary between the crust and the
on April 1, 2022
What are the process of erosion?
GeologyErosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water. A similar process, weathering, breaks down or dissolves rock, but does not involve movement. What are the four processes of erosion? Destructive waves erode through four main processes; Hydraulic Action, Compression, Abrasion and
on April 1, 2022
Is San Francisco at risk from earthquakes?
GeologyIs San Francisco safe from earthquakes? San Francisco is very vulnerable to earthquakes. Its three notable faults, covered below, are right-lateral strike-slip faults. This is a type of shearing force where the right block moves toward the fault and the left block moves away. Millions of Bay Area residents live near active fault zones. What
on April 1, 2022
What is a sedimentary rock made of?
GeologyClastic sedimentary rocks are made up of pieces (clasts) of pre-existing rocks. Pieces of rock are loosened by weathering, then transported to some basin or depression where sediment is trapped. If the sediment is buried deeply, it becomes compacted and cemented, forming sedimentary rock. How do we make sedimentary rocks? Erosion and weathering transform boulders
on April 1, 2022
What is scoria rock used for?
GeologyScoria Uses It is often used in landscaping and drainage works. It is also commonly used in gas barbecue grills. It can be used for high-temperature insulation. It is used on oil well sites to limit mud issues with heavy truck traffic. Is scoria the same as lava rock? Scoria is an extremely vesicular basaltic