### substance | earth | dirt:

Silt
* Most silt comes from the process of erosion of the top layer of earth.
* Some silts contain pollutants
  - enter waterways
* Some silts have bulk density
* Some silts have lower bulk density
  - several layers
  - texture
  - prevent respiration
* adds bulk to the soil, supplies minerals through chemical breakdown, and helps retain water.
* also clogs gills of fish and invertebrates.
* are located in water
  - the middle size and weight
* can also settle out on corals and interfere with feeding and recolonization
  - be heavy at times making visibility low
  - build up behind a dam to limit the amount of water stored in the reservoir
  - cause electrical shorting or mechanical malfunctions
  - fillin spaces between larger particles in till
  - kill salmon in the creek by clogging their gills and blocking their oxygen supply
  - plug up the alevin's gills
* causes a number of problems for both natural habitats and humans.
* collects on the shelf off-shore.
* covers gravel and chokes off the oxygen supply in the water.
* diminishes light penetration and eventually settles out on the seafloor.
* feels soft and silky, just like flour used for baking.
* floats in the water, clouding it and making it impossible to see the bottom.
* flour fine powder of ground rock.
* general term for sediment washed away by running water.
* have ability.
* helps identify rocks.
* is also a soil textural class in which silt principal separate
  - quartz, but the particles are much smaller than sand
  - carried by moving water
  - common in swamps, marshes,bayous, and along coastal saltwater areas
  - damaging spawning grounds in several streams flowing into the river
  - finer than sand, but coarser than clay
  - made up of smaller particules and has a floury feel
  - plackey, it dries in layers with a little fiber
* is the middle ground, with much smaller particles than sand and it feels slippery when wet
  - product of physical weathering , such as freezing and thawing
  - result from poor farming practices, overgrazing of stream banks and logging
* is the top pollutant of Iowa's waterways
  - water pollutant in Iowa, and farm fertilizers are high on the list
  - transported by streams or by water currents in the ocean
  - typically very rich in nutrients and water
  - usually the easiest type of particle to be entrain by wind
* much finer textured soil type than sand.
* particle of rock much smaller than sand.
* prevents effective drainage by blocking and displacing water.
* produces moist, well-drained soils needed for deciduous forests.
* soil particle whose size is between sand and clay.
* stops the passage of oxygen to the developing egg yolk and into the gills of tadpoles.
* usually has a floury feel when dry, and a slippery feel when wet.
* very fertile soil.
+ Siltstone: Sedimentary rocks
  * Silt is the product of physical weathering, such as freezing and thawing. Physical weathering does not involve any chemical changes in the rock, just its physical breaking apart.

Subsoil
* are clay, sandy clays, silty clays, and heavy clay loams
  - the bones of the earth
  - usually lighter in color, dense and low in organic matter
* consists of rock particles mixed with mineral nutrients.
* is dirt
  - the middle layer that contains large rocks alongside minerals washed out of the topsoil

Topsoil
* Most topsoil contains matter
  - nitrogen
  - has materials
* Some topsoil consists of sand.
* contain much higher levels of available phosphorus than subsoils.
* needs for growth.

Earth change
* is found in wisdom inner peace is found in acceptance
  - the way of nature
* occur in measurable patterns, which are seasonal and daily.
* take place over many scales of time and space.