Final answer:
Lava flows from a volcano would occur first, eventually cooling and solidifying to form fine-grained extrusive igneous rocks.
Step-by-step explanation:
The event that would occur first is lava flows from a volcano. This is because, in the formation process of igneous rocks, initially the molten material has to be extruded onto the Earth's surface as lava. Once the lava has flown out and is exposed to the environment, it begins to cool down and solidify to form igneous rock. This cooling and solidification might happen swiftly, particularly in the case of basaltic eruptions where basaltic lava flows quickly and can cover considerable distances before solidifying. These rapidly cooled lava flows lead to the creation of fine-grained, extrusive igneous rocks, also known as volcanic igneous rocks due to their surface-level formation.