Soil and its importance in CSI Introduction to soil Formation of soil Compositions of soil Types of soil Characteristics of soil Forensic examination and importance of soil

1. a square forensics
SOIL

2. INTRODUCTION
Soil is the upper layer of earth in
which plants grows, a black or dark
brown material typically consist of
mixture of minerals, water, gases,
and other organic decaying remains.
Soils are like fingerprints because
every type of soil that exists has
unique properties that act as
identification markers.

3. FORMATION
OF SOIL
Weathering is the mechanical or chemical process by
which rocks are broken down into smaller pieces.
As rocks are broken down, they mix with organic
materials, which are those materials that originate
from living organisms.
For example, plants and animals die and
decompose, releasing nutrients back into the soil.
Soil is highly heterogeneous in nature and varies
widely from place to place due to the effects of
wind, water, living organisms, mining and
agriculture. Thus, Soil from different places will have
different individual characteristics.

4. • SOIL HORIZONS
Soil horizons are distinct layers of soil that form naturally
in undisturbed soil over time. The formation of soil
horizons is called soil geomorphology and the types of
horizons are indicative of the soil order. Like other natural
processes, the age of the horizon increases with depth.
• Soil Horizon Names and Descriptions
• O: Decaying plants on or near surface
• A : Top Soil, Organic Rich
• B : Subsoil, Most Diverse Horizon and the Horizon with
the most subclassifications
• C : Weathered/aged parent material
• R : Bedrock

5. STEPS OF
SOIL
FORMATION

6. SOIL COMPOSITION

7. SOIL COMPOSITION
Soils are made of four main
components:
mineral matter (40 - 60 %)
soil water (20 - 50 %)
soil air (0 - 40 %) The soil pore space is filled
either by soil water or soil air. Mostly nitrogen,
oxygen and carbon dioxide
organic material (small percentage).
SOIL
BIOTIC
FACTORS
ABIOTIC
FACTORS
All the living
and once living
things in soil
Eg: plants and
insects
All non-living
things
Eg: Minerals,
water and air

8. TYPES OF SOIL
• •Sand
• •Clay
• •Silt
• •Peat
• •Chalk
• •Loam

9. CHARACTERISTICS OF SOIL
1. Color
Indicates its history as well as the compounds present in the soil.
2. Sediment
The original solid particles that were weathered and transported. This
could be in the form of a grain of rock that breaks off of the larger
parent material (larger version of rock). Soils can develop on these
sediments due to physical and chemical alteration.
3. Structure
Indicates whether a soil is composed of a single grain particle or not.
This is determined by the presence of peds (clumps).

10. 4. Soil Texture
Texture is determined according to the relative proportions of sand, silt, and
clay in the soil
5. Soil pH
Soil pH is a measure of soil acidity or alkalinity.
It is an important indicator of soil health
Natural soil pH reflects the combined effects of soil-forming factors:
parent material,
Time
relief or topography
climate
organisms

11. FORENSIC EXAMINATION OF SOIL
• Microscopic Observations
• Microscopical Observation with
Chemical Regents
• Ignition Test
• pH Measurement
• Particle size distribution
• Density distribution

12. FORENSIC IMPORTANCE
• Soil is a common form of physical evidence found at the scene of crime such as Hit and
Run accidents, Automobile collisions, Rape and Burglaries.
• A number of physical and chemical methods have been used for identification of source
as well as for comparison of two soils.
• Soil is highly individualistic in that there are an almost infinite number of different soil
types
• Soils may change rapidly over very short distances both horizontally and vertically
• Soil materials are easily described and characterized by color and by using various
analytical methods such as XRD (mineralogy) and spectroscopy (chemistry )
• Soil materials are easily located and collected using hand lenses or light microscopes
• National and international computerized databases of soil profile data and maps can be
readily accessed by police or soil scientists through the Internet