Question: of what are the north american cascade mountains an example
[{'answer': 'rugged topography', 'provenance': [{'wikipedia_id': '469258', 'title': 'North Cascades', 'start_paragraph_id': 4, 'start_character': 199, 'end_paragraph_id': 4, 'end_character': 216, 'bleu_score': 1.0, 'section': 'Section::::Geography.\n'}]}, {'provenance': [{'wikipedia_id': '469258', 'title': 'North Cascades', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 719, 'bleu_score': 0.9000491660231481, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11082598309231099913}, 'section': 'Section::::Geography.\n'}]}]