Question: who proposed the principles of stratigraphy to relatively date rock layers
[{'answer': 'William Smith', 'provenance': [{'wikipedia_id': '2992637', 'title': 'Relative dating', 'start_paragraph_id': 3, 'start_character': 92, 'end_paragraph_id': 3, 'end_character': 105, 'bleu_score': 1.0, 'section': 'Section::::Geology.\n'}]}, {'provenance': [{'wikipedia_id': '2992637', 'title': 'Relative dating', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 656, 'bleu_score': 0.969009723555843, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9930063736885717543}, 'section': 'Section::::Geology.\n'}]}]