Question: what part of the ice core is actually examined by scientists
[{'answer': 'Impurities in the ice', 'provenance': [{'wikipedia_id': '426456', 'title': 'Ice core', 'start_paragraph_id': 8, 'start_character': 0, 'end_paragraph_id': 8, 'end_character': 21, 'bleu_score': 1.0, 'section': 'Section::::Structure of ice sheets and cores.\n'}]}, {'provenance': [{'wikipedia_id': '426456', 'title': 'Ice core', 'start_paragraph_id': 9, 'start_character': 0, 'end_paragraph_id': 9, 'end_character': 325, 'bleu_score': 0.559223951919331, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11874654918123495382}, 'section': 'Section::::Structure of ice sheets and cores.\n'}]}]