-Field classification of igneous rocks (modified after R.B. Travis [1955]).

Contexts in source publication

Context 1

... figures are condensed and modified slightly from Travis' classifications, but the more detailed original classifications of Travis are acceptable. Figure 4-5 or appropriate American Geological Institute (AGI) data sheets are suggested for use when estimating composition percentages in classification. ...

Context 2

... zones may have minor or major lateral variations in the percentages of components within short distances at an exposure. The shear zone illustrated in figure 5-4 consists of 60 percent clay gouge and 40 percent rock fragments. Because the various components are not arranged in layers, the shear is of the uniform type. ...

Context 3

... of Logs Based on Laboratory Classification.-When logs are prepared using laboratory classifications (based on laboratory tests), the information must be presented on the log as shown in figure 11-4. The difference between a laboratory and a visual classification is depicted in figure 11-6. ...

Context 4

... of Custody.-Once all samples for a specific sampling task have been collected, the sampler(s) will complete the chain of custody record ( figure 12-4). Specific procedures for completing this form should be included in the work plan documents specific to the project. ...