Geometric Elements
Structural Geology Exercises
James S. Aber
The following examples are taken from metamorphic and igneous
rocks and unconsolidated sediment in western Norway.
| Interlayered felsic gneiss and amphibolite showing three sets of planar fractures exposed at Glasskartunnel. Layers and fractures are planar elements that cause the rock to break into rectangular blocks. Highway 14 in Bergen, Norway. |
| Amphibolite pod within gneiss, approximately 5 m across. White veins are secondary infillings of planar fractures within the dark amphibolite pod. Highway 14, Bergen, Norway. |
| Block of augen gneiss. Augens (eyes or knots) of feldspar are contained within banded metamorphic rock. The bands, known as foliation, are planar features. Askøy island, near Bergen, Norway. |
| Large glacial groove on crystalline bedrock surface. Scale pole is laid parallel to the linear groove; pole is 2 m long. Island of Herdla, near Bergen, Norway. |
| Small fold above a fault in late Pleistocene glaciomarine sediment. The yellow pen marks the linear axis of the fold, and the fault is a planar structure. Island of Herdla, near Bergen, Norway. |
Return to Structural Geology Exercises.
Text and images © J.S. Aber (2021).