Soil is produced by a complicated process that is influenced by factors such as temperature, rainfall, and the chemicals and minerals present int he material from which it forms.
Soil is part of the top layer of Earth's crust, where most plant grow.

Pedologists- people who study soil

Soil Types
Sand- the largest grain size. It is also composed of weathered rock.
Location: deserts, beaches, riverbeds

Clay- the smallest grain size. It is also composed of small particles adhering to each other.
Location: various
Silt- composed of medium- sized mineral particles
Location: sediment in riverbeds
Peat soil- soil with more than 20% decaying organic material and composed of decay organic material. It's also used with other soil types in fertilizer because of it's ability to retain water
Location: bogs, areas where water is retained by organic matter failing to decompose
Loam- made up of sand, silt and clay. Best soil for agriculture.
Location: various
Chalk- poor for agriculture, requires the addition of fertilizer and humus. Composed of alkaline soil with mineral stones
Location: Below the top soil

Soil Profiles
Soil from in horizons, or layers, that are more or less parallel to Earth's surface. The soil in each horizon has characteristic properties that differ from those in other horizons. Soil in a given area will have a unique profile or sequence of layers.
O horizon- upper horizon that is mostly made up of decaying organic matter, also called Humus
A horizon- beneath O horizon. The soil in that layer is dark. also called Topsoil and it's a mixture of of humus and mineral particles. Seeds sprout and plant roots grow in A horizon layer.
E horizon- beneath A horizon. The soil is lighter color. it's mostly made up of sand and silt. A leaching process takes place in E horizon which allows water to drip through the soil to carry away most of the minerals and clay originally present. also called Eluviation layer
B horizon- beneath E horizon. Contains clay and mineral deposits that have leached out from layer above is as water drips through from horizons above. Sometimes called Illuviation layer
C horizon- beneath B horizon. Mostly made up of broken up rocks. Plants and roots do not grow in this layer and also very little humus is found in this layer. Also called Regolith
R horizon- if there is a solid rock layer underneath all of the horizons except R, then it's part of R horizon. Also called Bedrock

Soil at Crime Scene

The soil was first used in 1800's to investigate crime scenes.
If soil has been recovered from the victim's shoes, it can determine where he/she was.

Trial Example
Enrique "Kiki" Camarena (1985)
Enrique was an undercover agent for the U.S. Drug Enforcement Agency, infiltrated drug dealings in Mexico and successfully helped to destroy millions of dollars of illegal drugs. Two drug tracking undercover agents were killed in a shootout by a group of drug dealers in Guadalajara, Mexico. Enrique and his partner were the agents. Soil samples taken from two bodies were found to contain an unusual combination of minerals and volcanic particles. Investigators used this evidence to prove that the men's bodies were originally buried in the mountains, far away from the shootout. The sol evidence, along with other evidence, eventually showed that the Mexican federal police had been involved in the murders.

Andreas Schlicher (1908)
Georg Popp was the investigator of the murder at this crime scene. Margaethe Filber was found dead in a field in Bavaria, Germany. Neighbors considered a man named Andreas Schlicher to be a possible suspect. Schlicher of course denied having anything to do with the crime and denied walking in the field where the murder took place. Police found out that Andrea's wife cleaned his shoes day before the murder happened. Andreas had his shoes muddy during the day the murder happen. The investigators, Georg Popp, took samples of soil around their house, at the crime scene and at the castle where Andrea's clothing was found. All of the soil samples matched up to his shoes and he was busted.

September, 2000. Oakbank, Adelaide Hills, South Australia. Wife and a son were reported missing. The following day, mother's car was found abandoned. Muddy and bloodstained shovel was recovered. The suspect was arrested. His name is Moonta. Moonta wouldn't tell the police where the bodies were, so they called Dr. Rob Fitzpatrick, who is a soil scientist. He took a soil sample off the shovel. After he ran some test on it, he believed that the soil came from an industrial gravel quarry, probably in the acid/low salt region of the Adelaide Hills. Case was solved thanks to the soil tests and Moonta was busted too.

Testing Techniques
Scientists compare the size, shape and solor of soil by looking at samples microscopically for soil types, amount of plants and animals material and particle size