Question: who were the two scientists who proposed the theory of seafloor spreading in the early 1960s
[{'answer': 'Harry Hess', 'provenance': [{'wikipedia_id': '145698', 'title': 'Seafloor spreading', 'start_paragraph_id': 3, 'start_character': 272, 'end_paragraph_id': 3, 'end_character': 282, 'bleu_score': 1.0, 'section': 'Section::::History of study.\n'}]}, {'provenance': [{'wikipedia_id': '145698', 'title': 'Seafloor spreading', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 499, 'bleu_score': 0.9754554449993441, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5460760939139939761}, 'section': 'Section::::History of study.\n'}]}]