Soil and Glass Study Guide

Sand

Coarse particles

Silt

medium particles

Clay

Fine particles

Soil from top to bottom

1. O- humus

2. A- Top Soil A

3. E- Sand and Silt E

4. B- Subsoil B

5. C- Broken rock C

6. R- Solid rock R

Humus

Decaying organic matter

Top soil

Dark; mixture of humus and minerals; plants sprout here

Sand and silt

Light; water leaches away most minerals

Subsoil

Clay and mineral deposits

Broken Rock

no plant growth, little humus

Solid Rock

Solid rock

Continential Sand

Composed mostly of quartz, mica, feldspar, and dark minerals like horneblende and magnetite

Volcanic Sand

• Dark as a result of black basalt or green olivine

• from mid ocean volcanoes

• young sand

Skeletal Sand

• made from remains of marine organisms

• less time to form than other types of sand

• only in tropical regions

Precipitate Sand

minerals from water that has evaporated

Immature

• found near the rocks that formed it

• found in areas not exposed to waves or currents

• bottom of bays, swamps, floodplains

Mature

• does not contain clay and has fewer jagged edges

• found on beach or desert dunes where weathering has taken place

X-Ray Diffraction

• determines the mineral composition of soil

• each mineral produces a unique pattern

• soil sample evidence continues to be questioned by courts as to its validity

Finding Gravesites

• gravesites cast unusual shadow on terrain

• best done when sun is low and shadows are easier to see

Cadaver Decomposition Island (CDI)

• is formed by the products (toxic and nutrient rich) emitted from the decomposing body

• vegetation is initially killed

As decomposition continues, soil quality improves

a small area containing different plants than the rest of the vicinity arises

Soil effects on a buried body

depth and rock content, soil moisture and underground water, soil texture, soil pH, and oxygen level

weathering

causes sand grains to become more rounded

When is a soil profile changed?

When evidence of a body is buried, also in a gravesite

Laminated glass

Two or more panes of glass bonded by a plastic middle layer

Tempered glass (safety glass)

Glass that has been subjected to extreme temperatures or chemical treatments to improve its strength

Bullet resistant glass (bulletproof)

Laminated and tempered glass composed of two layers- one hard and one soft

Becke Line

A submerged glass fragment that had a refractive index that differs from the liquid it is suspended in, a halo like ring appears around the edge of the glass. Halo like effect is called a becke line

Radial fracture lines (primary fracture)

Start at the point of impact and move outward

Concentric fractures (secondary fractures)

Form circles that share the same center

Refractive index

• light changes direction as it passes from one medium (air) to another medium (water)

• Change in direction is called refractive index