Lectures Part 6 - Most soils form by the weathering of rock...

Info icon This preview shows pages 1–32. Sign up to view the full content.

View Full Document Right Arrow Icon
ρ = “0.00” gm/cm 3 Most soils form by the weathering of rock and minerals into smaller and chemically transformed pieces ρ = “1.00” gm/cm 3 ρ =2.65 gm/cm 3 Air Water Solid
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
ρ organic matter = “0.5” gm/cm 3
Image of page 2
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
Stuff, regolith, overburden, particuLate matter etc. at the Earth surface cannot be a “soil” unless it shows some geochemical and structural changes that produce soil HORIZONS.
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Well-developed soil profile.
Image of page 6
Soils form by four main categories of processes. Addition of materials (volcanoes, dust) Chemical transformation (weathering) Transfers (redistribution dissolved species) Removal (removal of dissolved species)
Image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Each soil forming process results in an exchange of matter and energy.
Image of page 8
dust storms, volcanoes
Image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
In order for the upper part of the pedosphere to be a soil it must be a natural body of weathered mineral material with some organic matter, organized into parallel layers called horizons .
Image of page 10
Soil Layers O1 Undecomposed litter O Horizon Organic Plant Residues O2 Partly decomposed debris A1 Zone of humus accumulation A2 Zone of strongest leaching A Horizon Zone of eluviaiton (leaching) A3 Transition to B horizon B1 Transition to A horizon B2 Zone of strongest deposition Solum, True Soil B Horizon Zone of illuviation (deposition) B3 Transition to C horizon Regolith, Weathered Material C Horizon Parent Material C Unconsolidated rock R Layer - Bedrock R Consolidated rock See “Fundamentals of Soil Physics”, D. Hillel, 1980, Academic Press.
Image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
In real life however, soil horizons may or may not be readily apparent to the eye.
Image of page 12
….that is because often the horizons are characterized by chemical differences that may or may not have a visual signature. Careful visual observations however are still useful to soil scientists.
Image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Soils generally are less than 2 meters thick,
Image of page 14
and they form a discontinuous membrane around the Earth.
Image of page 15

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Soil formed on unconsolidated river sediments.
Image of page 16
Sometimes recent river sediments can bury an old, previously formed soil.
Image of page 17

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Soils form on ancient sand dunes,
Image of page 18
on igneous rock,
Image of page 19

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
on metamorphic rock,
Image of page 20
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern