IDS PHOTO 29
Interesting features near the northern margin of a (Cretaceous?) mafic dike on the east side of Woods Lake. "Plume" shaped structures, 5-15 cm in length, extend from close to the margin toward the center of the dike. Rock texture changes within each plume; plagioclase phenocrysts are small (1-2 mm) closest to the margin and increase in size to >1 cm, often with amphibole cores. Closer to the center of the dike (>20 cm from the margin), the dike has medium grain size and is sparsely porphyritic. Compare with IDS Photo 35.