Occurrence of Attributes in Original Text

The text related to the cultural heritage 'Mammoth Cave National Park' has mentioned 'Elevation' in the following places:
Occurrence Sentence Text Source
The resurgent water from these springs typically flows briefly on the surface before sinking underground again at elevation of the contact between the sandstone caprock and the underlying massive limestones.
The contact between limestone and sandstone can be found by hiking from the valley bottoms to the ridgetops: typically, as one approaches the top of a ridge, one sees the outcrops of exposed rock change in composition from limestone to sandstone at a well-defined elevation.
Without access to the closely held survey data, Martel was permitted to make barometric observations in the cave for the purpose of determining the relative elevation of different locations in the cave.
According to the United States Department of Agriculture, the Plant Hardiness zone at Mammoth Cave National Park Visitor Center at 722xc2xa0ft (220 m) elevation is 6b with an average annual extreme minimum temperature of -3.2xc2xa0xc2xb0F (-19.6xc2xa0xc2xb0C).