Sources and References

Primary texts — Tarbuck, E.J., Lutgens, F.K., and Tasa, D., Earth: An Introduction to Physical Geology, 13th ed., Pearson, 2020; Goodman, R.E., Engineering Geology: Rock in Engineering Construction, Wiley, 1993.

Supplementary texts — Waltham, T., Foundations of Engineering Geology, 3rd ed., CRC Press, 2009; West, T.R. and Shakoor, A., Geology Applied to Engineering, 2nd ed., Waveland, 2018.

Online resources — MIT OCW 12.001 “Introduction to Geology”; Geological Survey of Canada open publications; USGS professional papers and open-file reports; BGS OpenGeoscience; ISRM suggested methods for rock mechanics testing.

Chapter 1: Materials of the Earth

1.1 Minerals

A mineral is a naturally occurring, inorganic, crystalline solid with defined chemistry. Eight elements account for 99% of the crust: O, Si, Al, Fe, Ca, Na, K, Mg. Silicate minerals dominate; their tetrahedral \( [SiO_4]^{4-} \) units link in chains, sheets, and networks (feldspars, micas, olivine, pyroxenes, amphiboles, quartz).

Physical properties (hardness, cleavage, luster, density, color, streak) allow field identification. Mohs hardness scale: talc 1, gypsum 2, calcite 3, fluorite 4, apatite 5, orthoclase 6, quartz 7, topaz 8, corundum 9, diamond 10.

1.2 The Rock Cycle

Rocks cycle among three groups through geological processes:

• Igneous: solidified from magma. Intrusive (slow cooling, coarse: granite, gabbro) vs. extrusive (rapid cooling, fine: rhyolite, basalt). Classified by silica content (felsic, intermediate, mafic, ultramafic) and grain size.
• Sedimentary: accumulated and lithified sediments. Clastic (sandstone, shale), chemical (limestone, evaporites), biogenic (coal, chalk).
• Metamorphic: recrystallized under heat/pressure without melting. Foliated (slate, schist, gneiss) or non-foliated (marble, quartzite).

Each group carries distinctive engineering properties: granite is strong and durable; shale is weak and moisture-sensitive; marble is workable but soluble.

1.3 Engineering Classification of Rocks and Soils

Rocks: ISRM classes by uniaxial compressive strength (extremely weak < 1 MPa, weak 5-25, moderately strong 25-50, strong 50-100, very strong 100-250, extremely strong > 250). Rock mass quality: RMR (Bieniawski), Q-system (Barton), GSI (Hoek).

Soils (Unified Soil Classification System, USCS): grain size (gravel, sand, silt, clay), plasticity (liquid limit, plasticity index), organic content. Atterberg limits frame plasticity: liquid limit (LL), plastic limit (PL), shrinkage limit (SL).

Chapter 2: Structural Geology and Tectonics

2.1 Plate Tectonics

The lithosphere is broken into plates that move over the asthenosphere at cm/year rates. Boundary types: divergent (mid-ocean ridges), convergent (subduction, collision), transform (strike-slip). Tectonic setting explains the distribution of earthquakes, volcanoes, and mountain belts, and informs regional hazard and resource endowment.

2.2 Deformation Structures

Brittle deformation: joints (planar fractures without displacement) and faults (with displacement). Fault types: normal (extensional), reverse and thrust (compressional), strike-slip (shear). Fault zones are weakened rock masses of engineering significance: dams, tunnels, and foundations across active faults require specific measures.

Ductile deformation: folds (anticlines, synclines, monoclines) at geological timescales. Folding and faulting together produce complex geology with anisotropic strength and permeability.

2.3 Rock Mass Characterization

Rock masses are rarely intact; discontinuities (bedding, joints, faults, schistosity) dominate engineering behavior. Parameters: orientation (dip/dip direction), spacing, persistence, roughness, aperture, filling, groundwater. Scanlines and window surveys characterize rock masses quantitatively.

2.4 Stress in the Crust

In situ stresses comprise vertical (overburden, \( \sigma_v = \gamma z \)) and horizontal components. At shallow depth, horizontal stress can exceed vertical due to tectonic compression (\( K = \sigma_h/\sigma_v \)). Measurement by overcoring, hydraulic fracturing, and borehole breakout analysis. Stress rotation near excavations concentrates forces at corners and weak planes.

Chapter 3: Geology of Canada

3.1 Regional Framework

• Canadian Shield: vast Precambrian craton, strong crystalline rocks; hosts much mineral wealth (Ni, Cu, Au, U, diamonds).
• Appalachian orogen (Atlantic provinces): deformed Paleozoic sedimentary and metamorphic.
• Interior Plains: flat-lying Phanerozoic sediments; petroleum and potash.
• Cordillera (western Canada): mountain-building from Jurassic onward; complex structure.
• Innuitian and Arctic platform: high arctic, permafrost dominant.
• Hudson Platform and other shelf areas with sedimentary cover.

3.2 Quaternary Geology

Most of Canada experienced repeated Pleistocene glaciations. Resulting features: till (unsorted), glaciofluvial (sorted), glaciolacustrine, eskers, drumlins, moraines. Post-glacial isostatic rebound continues; Hudson Bay region rises at ~1 cm/year. Engineering implication: variable, often non-uniform foundations; “dirty” gravels and silts with wide grain-size ranges.

3.3 Seismic and Volcanic Hazard

Significant seismic hazard in British Columbia (Cascadia subduction, Queen Charlotte fault), the St. Lawrence Valley, and the Ottawa–Gatineau region. Active volcanism limited to western Canada. National Building Code references seismic hazard maps published by NRCan.

Chapter 4: Surface Processes

4.1 Weathering

Physical (freeze-thaw, thermal stress, salt crystallization, unloading) and chemical (dissolution, hydrolysis, oxidation, hydration) weathering break rock into soil. Rate depends on climate: chemical weathering dominates in warm humid climates, physical in cold or arid ones. Engineers should not confuse weathered rock with fresh rock: strength may drop by an order of magnitude within a meter of the ground surface.

4.2 Soil Formation and Horizons

Soils develop over time with horizons O (organic), A (topsoil), B (subsoil), C (weathered parent material), R (unweathered bedrock). Engineering classifications typically ignore pedogenic horizons; geotechnical investigations capture them when relevant (organic soils compress dramatically; hardpans concentrate groundwater).

4.3 Mass Wasting

Landslides: falls, topples, slides (rotational, translational), flows, creep. Stability reflects driving forces (gravity, water pressure) versus resisting (shear strength of materials). Factor of safety \( FS = \tau_{available}/\tau_{mobilized} \); design typically requires FS > 1.3-1.5. Climate change alters precipitation, freeze-thaw, and permafrost, reshaping mass-wasting hazard.

4.4 Water Action

Streams: discharge, sediment transport (bed load, suspended load), erosion and deposition. Bankfull discharge shapes channel geometry; recurrence intervals (2-year, 100-year) inform bridge and levee design. Channel morphology (meandering, braided) governs scour and deposition patterns.

Groundwater: Darcy’s law \( q = -k \nabla h \). Aquifers (confined, unconfined), aquitards, transmissivity \( T = kb \), storativity \( S \). Groundwater flow paths determine contaminant transport and dewatering requirements for excavations.

Chapter 5: Ice and Wind

5.1 Glacial Processes

Continental and alpine glaciers shape landscapes. Erosional: cirques, arêtes, U-shaped valleys, fjords, striations. Depositional: moraines (terminal, lateral, medial), outwash plains, kames, kettles. Engineering impact: erratics (transported boulders) in excavations; ice-contact deposits with erratic stratigraphy; glaciolacustrine clays prone to landslides and sensitive to disturbance (Leda clay in Ottawa Valley).

5.2 Periglacial and Permafrost

Permafrost underlies ~50% of Canada. Ground remains below 0 °C for ≥ 2 consecutive years; active layer thaws seasonally. Engineering problems: thaw settlement beneath heated buildings, frost heave under pipelines and roads, slope instability (solifluction), infrastructure design (thermosiphons, elevated piles, insulation, refrigeration). Climate warming degrades permafrost—changes already observed in northern Canada require continuous adaptation.

5.3 Wind and Aeolian Deposits

Dunes (barchan, transverse, longitudinal), loess (wind-blown silt), desert pavement. Wind erosion concerns for arid agriculture and construction. Loess deposits (southern Manitoba, parts of prairies) are highly porous and can collapse on wetting—a geotechnical concern in foundations.

Chapter 6: Tools, Time, and Maps

6.1 Topographic Maps

Contour lines, spacing, scale, symbols. Slope \( = \Delta elevation/\Delta horizontal \). Hydrographic features, built infrastructure, geological overprints. Modern equivalents: LiDAR-derived DEMs, orthoimagery, GIS layers.

6.2 Geological Maps

Rock units identified by color and symbol; structural symbols for strike-dip-plunge; cross-sections reveal subsurface geometry. Interpreting geological maps is foundational: what material is present at a given site, how does it vary, what structures affect it?

6.3 Geologic Time

Relative dating: superposition, cross-cutting relations, inclusions, faunal succession. Absolute dating: radiometric methods (U-Pb, K-Ar, \( ^{14} \)C) with appropriate half-lives. Geologic timescale: eons, eras, periods, epochs, ages; engineering attention to Quaternary (last 2.6 Ma) for most recent processes affecting contemporary ground.

6.4 Site Investigation

Desk study, field reconnaissance, drilling (auger, rotary, sonic), sampling (disturbed, undisturbed), logging (visual, geophysical), laboratory testing. Site investigation budgets are traditionally underspent—resulting change-order costs during construction routinely exceed the savings. Observational method (Peck) updates design with field data.