UPCAT GEN SCIENCE

• is a collective layer of gas that envelopes the Earth. It can be further divided into different layers based on characteristics.

  
  

  The blank is essential to life on Earth because (1) It shields the Earth and its inhabitants from harmful ultraviolet (UV) radiation from the Sun; (2) it maintains the warmth of the Earth's surface; and (3) it contains all of the essential gases needed to support life. More about the atmosphere will be covered later on.

  Atmosphere
• 4.5 billion


  age of earth
• refers to the bodies of water consisting of freely flowing bodies of water found on the surface of the Earth, as well as water reservoirs stored below the ground as groundwater.

  hydrosphere
• Hydrosphere covers how many percent

  71%
• refers to the narrow band on the Earth's surface where all biological life resides. This could range from bustling cities, lush tropical rainforests, arid deserts, or even extreme environments like the bottom of the ocean floor.

  Biosphere
• the largest out of all the spheres, extending from the surface of the Earth down to its center. It comprises external processes that we can observe on the surface and internal processes deep within

  Geosphere.
• This is the thinnest and outermost layer of the Earth.


  Crust
• 2 types of Crust

  oceanic and continental
• Continental Crust


  is the older and more buoyant type of crust. It has an average thickness of 35 km but can be more than 70 km thick in mountainous regions. It has an average composition of granite with a 2.7 g/cm3 density.
• Oceanic Crust


  is the younger and denser type of crust. It has an average thickness of 7 km, much thinner than the continental crust. It comprises a 3.0 g/cm3 density of basalt, dark igneous rock.
• comprises most of the Earth's volume (more than 80%) and begins where the crust ends, down to a depth of 2,900 km.

  Mantle
• The discontinuity between the upper mantle and the lower mantle is known as

  Repetti Discontinuity
• The boundary between the crust and mantle

  Mohorovicic discontinuity
• begins at the mantle-core boundary. scientific investigations concluded that its composition comprises a Fe-Ni (iron and nickel) alloy.

  Due to its composition and the pressure conditions at depth, it is calculated to have a whopping density of around 11 g/cm3.

  Core
• the transition zone between the mantle and the core.

  Gutenberg Discontinuity
• is a thick and brittle layer comprising the entire crust and uppermost layer of the upper mantle.

  It has an average thickness of 100 km but can reach up to 300 km in the thickest portions of continents.

  Lithosphere
• is a mechanically weak layer consisting of the lower portion of the upper mantle, extending to 660 km.

  Contrary to popular belief, it is not a "sea of molten rock." The upper mantle comprises an Mg- and Fe-rich rock called peridotite.

  Asthenosphere
• The upper mantle comprises an Mg- and Fe-rich rock called


  Peridotite
• Beneath the asthenosphere, comprised of the lower mantle, reaching the 2,900 km depth.

  Mesosphere
• The dominant rock type in mesosphere is a silicate rock called


  Perovskite
• Unlike all the other mechanical layers, the blank is the only one made out of liquid-melted Fe-Ni alloy, to be exact. The liquid nature of this layer can be attributed to extremely high temperatures (more than 3000°C!) that melt Fe, Ni, and all other elements.

  Outer Core
• The outer-inner core boundary is also known as the

  Lehmann Discontinuity
• Despite the extreme temperature, the overwhelming pressure in this layer forces the inner core to be a solid ball of mostly Fe.

  Temperatures in the inner core are similar to the temperatures of the surface of the Sun—around more than 5400°C.

  Inner Core
• are building blocks of rocks.

  Minerals
• To be considered a mineral, it must be the following:

  Naturally-occurring

  Inorganic

  definite chemical composition

  crystalline structure

  Homogeneous solid
• It refers to the wavelengths of light reflected by the minerals

  color
• It describes how light is reflected from the mineral's surface

  luster
• This refers to the shape of each crystal or an aggregate of crystals. Although a single mineral can occur in various shapes, crystal habit can still be an identifying feature in certain minerals.

  Crystal habit or Shape
• This is the color of the mineral when it is powdered. Some minerals have different streak colors than their apparent color, which becomes a useful property when differentiating similar-looking minerals.

  Streak
• This refers to how resistant a mineral is to scratching

  Hardness
• is a tool used to describe a mineral's hardness relative to other minerals.

  Mohs' Scale
• refers to the tendency of a mineral to break along preferred planes called zones of weakness. A fracture is produced if a mineral doesn't break along zones of weakness.

  Cleavage or Fracture
• This describes how well a mineral handles stress, such as breaking, crushing, bending, or tearing.

  Tenacity
• This refers to the ratio between a mineral's weight and the weight of a specific volume of water (Water has a specific gravity of 1). Heavy minerals such as gold or platinum have very high specific gravity, whereas light minerals such as graphite have low specific gravity.

  Density
• This refers to how well light travels through a mineral. Transparent minerals allow almost all light to travel through the mineral (e.g., some quartz and calcite). Translucent minerals only allow some light to travel and exit the mineral, giving off a cloudy or murky appearance (e.g., smoky quartz, gypsum). Opaque minerals do not allow light to travel through (e.g., gold, copper, pyrite).

  Diaphaneity
• This describes the magnetic property of a mineral. Magnetite is an example of a strongly magnetic (strongly attracted to magnets) mineral. There are also moderately and weakly magnetic minerals such as chromite, ilmenite, and columbite. A lodestone is a type of magnetized magnetite that can magnetically attract other materials.

  Magnetism
• This describes a mineral's reaction to a strong acid such as HCl (hydrochloric acid). This is due to the chemical reaction between CaCO3 and HCl in carbonate minerals and rocks. Highly effervescent minerals like calcite exhibit intense "fizzing" or "bubbling" when exposed to HCl. Some minerals are weakly effervescent and only show light "fizzing," such as rhodochrosite and azurite.

  Effervescence
• You may have heard that some geologists lick rocks. While that may seem a bit wacky and weird, geologists indeed lick and even smell rocks to identify them. Halite, more popularly known as "rock salt," is a mineral that gives off a salty taste. Other examples are borax which gives off a sweet taste; epsomite which tastes bitter; and chalcanthite, which is sweet but slightly poisonous. Their "rotten egg" smell can identify sulfur and pyrite.

  Odor and Taste
• To this date, thousands of different minerals have been identified and named, and the list grows every year! However, only a few of these minerals are abundant on the Earth's crust, called

  Rock Forming Minerals
• the most common mineral group

  silicates