| 31. | The Upper Cretaceous rock units confine the Edwards Aquifer within the Edwards Group and Georgetown Formation.
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| 32. | The rock unit in which the falls are formed is referred to as the Jeffersonville limestone.
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| 33. | All these rock units together form a super sequence of rock known as the Grand Staircase.
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| 34. | This rock unit represents a forested setting of rivers and lakes that formed between episodes of volcanism.
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| 35. | Geologists employ biostratigraphy, the use of index fossils, for dating sedimentary rock units like the Coon Creek.
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| 36. | This can be used to qualitatively identify thinning or thickening of a rock unit in different directions.
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| 37. | Locally it immediately overlies other rock units.
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| 38. | Rock units are typically represented by colors.
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| 39. | The Upper Cretaceous rock units confine the Edwards Aquifer within the Edwards Group and the Georgetown Formation.
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| 40. | The majority of the rock units shown on the 1976 map were mapped in 1973 by reconnaissance methods.
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