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School of Environment, Education and Development

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BSc Geography and Geology
Benefit from a wide range of optional topics and practical trips on this combined degree.

BSc Geography and Geology / Course details

Year of entry: 2018

Course unit details:
Igneous Petrology

Unit code EART20131
Credit rating 10
Unit level Level 2
Teaching period(s) Semester 1
Offered by School of Earth and Environmental Sciences
Available as a free choice unit? Yes


This course provides a thorough coverage of the main types of igneous process and the rocks produced. It builds on material learnt in First Year courses on Igneous & Metamorphic Rocks and on Chemistry of the Earth. It covers magma generation in the Earth, differentiation processes, and the igneous rocks found in different tectonic settings, as well as the analytical, graphical and theoretical methods applied to understanding these processes and rocks. The module also provides a firm foundation for interpreting igneous rocks encountered elsewhere in the degree programme, in particular during the 2nd Year Easter fieldcourse to Glencoe and the variety of igneous rock types that occur in many of the independent mapping areas.


Unit title Unit code Requirement type Description
Planet Earth: Its Climate, History and Processes EART10111 Pre-Requisite Compulsory
Igneous & Metamorphic Rocks EART10242 Pre-Requisite Compulsory
Chemistry of the Earth EART10321 Pre-Requisite Compulsory
Mineralogy EART10501 Pre-Requisite Compulsory


To become familiar with the compositions and mineralogies of the major igneous rock types.  To understand the processes responsible for their formation and the dependence of these on tectonic setting.  To develop an appreciation of some of the key skills required to interpret igneous rocks and processes.

Learning outcomes

On successful completion of the course, students will:

  • be able to discuss the processes responsible for producing the diversity of igneous rock types, and illustrate using real and theoretical examples.
  • have developed skills in observing and recording the important features of igneous rocks in thin section and hand specimen, and in interpreting observations.
  • be able to use numerical and graphical techniques to solve igneous petrological problems.


The course consists of a 1-hour lecture plus 2-hour practical each week. Practicals will involve examination of thin sections and hand specimens, and some paper exercises. You will produce an atlas of igneous rocks based on digital photographs of the practical samples.


Week 1:

No class (France field course).


Week 2:

Lecture: Introduction: Why does magmatic activity occur? What is magma? Introduction to igneous rock nomenclature and classification.

Practical: Revision of mineral identification under the optical microscope.


Week 3:

Lecture: Phase relations in binary systems.

Practical: Binary and ternary phase diagram exercises.


Week 4:

Lecture: Basalts I: Classification, CIPW norm, eruptive processes and products, basalt textures.

Practical: Textures of basalts in thin section. Exercise on CIPW norms. Practice at petrographic description.


Week 5:

Lecture: Basalts II: Mid-ocean ridge basalts, oceanic island basalts, variation diagrams.

Practical: Exercise on variation diagrams.


Week 6:

Lecture: Gabbroic rocks: classification, internal structures and layering, textures.

Practical: Samples from the Skaergaard layered intrusion and the Palisades Sill.


Week 7:

Lecture: Trace elements and isotopes in igneous petrology.

Practical: Using trace elements to interpret fractionation processes and magma.


Week 8:

Lecture: Ultramafic rocks and the Earth’s mantle, mantle melting.

Practical: Samples from the Earth’s mantle.


Week 9:

Lecture: Subduction zone magmatism.

Practical: Andesites, dacites and rhyolites.


Week 10:

Lecture: Granites.

Practical: S-type and I-type granites.


Week 11:

Lecture: Styles of extrusion and intrusion of intermediate to acid magmas; their products in the geological record.

Practical: Blackboard Test. Products of explosive volcanism.


Week 12:

No class. Independent work on rock atlas.

Assessment methods

Method Weight
Other 40%
Written exam 60%

Production of igneous rocks atlas (30%)

BB tests to be done in students' own time, weeks 2 - 6 (2% each = 10% total)

Written Exam (60%)

Feedback methods

Every week you will have a 2-hour practical session in which you will look at samples and data related to that week's lecture. In these sessions you will be able to ask the lecturer and demonstrators questions about the lecture and practical material, and you will be given verbal feedback on your work. Further feedback on the practicals will be provided on-line. Answers and feedback to each Blackboard test will also be available on-line, as soon as the test availability period ends. You will receive individual feedback for your igneous rock atlas in January, and feedback on your January exam will be available in a session in March when you will be able to go through your marked exam script with the lecturer.

Recommended reading

Recommended: Gill, Igneous rocks and processes: a practical guide, Wiley-Blackwell.

Additional useful reading: Best, Igneous and Metamorphic Petrology, 2nd edition, Blackwell.

Study hours

Scheduled activity hours
Lectures 10
Practical classes & workshops 20
Independent study hours
Independent study 70

Teaching staff

Staff member Role
Margaret Hartley Unit coordinator

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