I'm convinced we can amass images for an entire 1st year university geology course using only volcano stamps. Find a relevant stamp in the 'Themes' galleries, copy and paste it here, and describe the geology element it represents.
top of page
bottom of page
Aaland 1993. 2,00mk. Diabase dyke.
This stamp shows a dolerite or diabase dyke (diabase is the preferred name in North America, while dolerite is the preferred name in the rest of the English-speaking world). Such dykes occur in regions of crustal extension and often occur in swarms of hundreds of individual dykes or sills radiating from a single volcanic centre.
Dolerite is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Can anyone provide more info?