| Below the lowest sheet of largely coherent mafic igneous rocks is the Phyllite-Quartzite Group, a sequence of turbidites and black mudrocks. |
| She introduces cross-hatching as an internal element in wheeling and receding shapes that recall igneous rocks scored with veins of quartz. |
| The occurrence of these felsic extrusive igneous rocks potentially provides key information on the complex interplay of magmatism and tectonics. |
| It has also been found in silica-poor igneous rocks, such as syenite, nepheline syenite, serpentinite, and lamprophyre. |
| They were primarily studying the igneous rocks in the region but still managed to bag a few good fossils. |
| The crest of the Blue Ridge is usually underlain with Precambrian or Cambrian igneous rocks. |
