Mike Tuke’s

GEOLOGICAL SKILLS Below are listed some geological skills and examples of their use. Skills relating to maps are described under the Outcrop Patterns section. Measuring and plotting size frequency Phenocrysts in a porphyry Clasts in a conglomerate or breccia Fossils either loose, or in a rock Sieving sand Width of dykes Sizes of vesicles Measuring and plotting orientation Give students photocopies of the rock or sediment. Students draw lines along the maximum length of each item and then measure the angle of the line to a master line already drawn on the photocopy, which may represent the north direction,. The data are plotted on a tally sheet and then onto a rose diagram. Phenocrysts in a porphyry Clasts in a conglomerate or breccia Recent sediments (e.g. imbrication in the bank of a stream) Belemnites, crinoids, bivalves or other fossils Joints Faults on maps Dykes from field data Sedimentary structures from field data Point counting Percentage of phenocrysts and groundmass in a porphyry Percentage of clasts and matrix in conglomerate or breccia Vesicles/amygdales in a basalt

Earth Science Activities and Demonstrations