Figure 2.02. Chilled margin on diabase dike. White plagioclase phenocrysts are absent from the margin of this diabase dike from Hull, MA, USA. The chilled margin is evidence that the host rock (Dedham granodiorite) was cool when the dike was intruded. The field of view is 35 cm across. The chilled margin is 10-14 cm wide on a dike that is about 160 cm across. Use your mousewheel to zoom and pan to see details. Click on the "Show Lres" button to see a full dike view. John Brady photo.