In his journal, Goethe shows a marked interest in the geology of Europe's southern regions. He demonstrates a depth and breadth of knowledge in each subject. Most frequently, he pens descriptions of mineral and rock samples that he retrieves from the mountains, crags, and riverbeds of Italy. He also undertakes several dangerous hikes to the summit of Mount Vesuvius, where he catalogues the nature and qualities of various lava flows and tephra. He is similarly adept at recognizing species of plant and flora, which stimulate thought and research into his botanical theories.