Site Analysis: Ecology and Geology

• Site analysis involves assessing a site based on various ecological considerations
• Site analysis studies natural factors like geology, geomorphology, hydrology, vegetation, wildlife, and climate

Ecology

• Ecology is the biological study of the relationships between organisms and their surroundings
• Ecology is also a political movement focused on environmental protection, specifically against pollution

Geology

• Geology is a natural factor in site analysis
• Geology studies the origin, composition, structure, and history of the Earth

Igneous Rocks

• Igneous rocks are formed through the crystallization of liquid rock
• Andesite can be used as aggregate or fill in construction and roads
• Obsidian was historically used for tools like knives and arrowheads
• Basalt is commonly crushed for aggregate in construction projects
• Granite is used in buildings, bridges, paving, monuments, countertops, tile floors, and stair treads
• Pumice serves as aggregate in lightweight concrete, landscaping, and as an abrasive in industrial and consumer products
• Tuff, easy to work with, has been used as a building material and for statues since ancient times

Sedimentary Rocks

• Sedimentary rocks form when igneous rocks weather and erode into particles
• These particles are then transported by erosional processes
• Finally, the particles are deposited in layers within rivers and oceans
• Uses for Bituminous include road and roof construction, industrial purposes, carpet tiles, paint, and waterproofing
• Chert can be used as decorative aggregates for buildings and gardens and as material for cutting tools
• Flint can be used for Interior: decorative aggregates, home, interior decoration
• Flint can be used for Exterior: As bldg. stone, as facing stone, garden decoration, office buildings, paving stone

Metamorphosed Rocks

• Metamorphosed rocks form from sedimentary rocks
• Sedimentary rocks are pushed to deeper levels within the Earth
• This causes the sedimentary rocks to transform due to changes in pressure and temperature
• State is often used for roofing, flooring, and flagging because of its durability
• Marble is used for its optical properties in cosmetics, paint, and paper
• Schist is used as construction aggregate, building stone, or decorative stone

Geomorphology

• Geomorphology studies the origin, nature, and distribution of landforms

Geomorphology Considerations

• Soil composition and appropriate land uses should be considered together in site planning
• Soil surveys can help guide site selection for residential, industrial, and other developments

Soil

• Several features, or properties, are used to describe soil for use in site design
• Two important soil features are composition and texture
• These two features are very meaningful, and from these bearing capacity, internal drainage, erodibility, and slope stability can be inferred

Soil Properties

• Soil properties include composition and texture
• Composition refers to the materials that make up soil: mineral particles, organic matter, water, and air

Soil Composition

• Mineral particles comprise 50% to 80% of the soil volume
• Soil is the all important skeletal structure of the soil
• Sand and gravel particles provide for the greatest stability, usually yield a relatively high bearing

Drainage

• Poor drainage means gravity water is not readily transmitted by the soil
• Poorly drained soil is frequently or permanently saturated
• Poor drainage can be caused by the local accumulation of water, a rise in the level of groundwater, or particle size
• Good drainage refers to the soil's ability to transfer gravity water downward

Three ways water moves through soil

• Infiltration: The rate at which water penetrates the soil surface
• Is usually measured in cm or inches per hour
• Permeability: The rate at which water moves through a given volume of soil
• Is also measured in cm or inches per hour
• Percolation: The rate at which water in a soil pit or pipe within the soil is taken up by the soil
• Is usually mainly in wastewater absorption tests and measured in inches per hour

Water

• Water content in soil varies with particle size, local drainage, topography, and climate
• Most water occupies the spaces between particles
• Only in organic soils do the particles themselves absorb measurable amounts of

Air

• Air is what occupies the remaining space in soil not occupied by water
• In layers where groundwater is formed by gravity water in the subsoil and underlying rock, there is an absence of air

Soil Texture

• Soil texture is how one describes the composite sizes of particles in a soil sample
• Texture can be divided into 12 basic terms, at the center of which is Class LOAM
• Sand, Loam, Clay which is an intermediate mixture of 40% sand, 40% silt, and 20% clay

Topography and Slopes

• Understanding slope forms for site design requires understanding of local geologic, soil, hydrologic, and vegetative conditions

Slope Form

• The slope profile is a silhouette of a slope drawn to known proportions
• The proportions measure distance on the horizontal axis and elevation on the vertical axis

Four Basic Slope Forms

• Straight, S-shape, concave, and convex

Angle of Repose

• Angle of repose is the angle at which soil can be safely inclined and beyond which it will fail

Topographic Map

• A topographic map is a map of a portion of Earth
• These maps describe the shape of Earth's surface using contour lines

Contours

• Contours are imaginary lines that join points of equal elevation on the surface of the land
• Contours provide measurement of the height of mountains, depth of the ocean bottoms, and steepness of slopes

Map Reading

• Map reading is identifying features on a map using symbols and signs
• Map reading relies on geological, relief, drainage, vegetation, and soil maps

Essentials of a Map

• Maps need a title, scale, key, margin/boundary/frame, north direction/compass orientation, and date