What Is This Karst Landform? N 4721181 W 12194142

What Is This Karst Landform N 4721181 W 12194142 How Did It Fo

1. What is this karst landform (N 47.21181 W 121.94142), how did it form, and what do the hatchered contours mean (that you can see in Acme Mapper topo tap)?

a. This blind lake formed when the hole to the underground cavern system plugged up with silt. The hatchered contours indicate that the area collects water.

b. This depression formed when the limestone roof fell into an underground cavern, and this is what the hatchered contours mean.

c. This doline formed by the dissolution of granite rock, and the hatchered contours tell you that the location is a depression.

d. This doline formed through limestone dissolution, and the hatchered contours tell you that the location is a depression.

Paper For Above instruction

Karst landforms are unique land features resulting from the dissolution of soluble rocks, primarily limestone, but also including halite (salt). The formation and morphology of these landforms provide insights into subsurface geological processes and surface hydrology. In this discussion, we examine four specific karst landforms identified by their geographic coordinates, exploring their formation, characteristics, and the significance of their topographical features such as hatchered contours.

1. The Karst Landform at N 47.21181 W 121.94142

The landform at these coordinates represents a type of depression known as a doline or sinkhole, formed predominantly through the dissolution of limestone. The options provided offer different interpretations of its origin. The correct explanation is that this feature is a doline formed by the dissolution of limestone, with hatchered contours indicating a depression. This interpretation aligns with typical karst processes where slightly acidic water percolates through cracks and fissures, gradually dissolving the limestone and enlarging these features into depressions or sinkholes (Ford & Williams, 2007). Hatchered contours on a topographical map reveal areas of depression or convergence points where water accumulates, confirming the presence of a basin or sinkhole.

2. The Final Point of Culverson Creek (N 37.94188 W 80.45261)

This landform marks the endpoint of Culverson Creek, situated at its lowest elevation, where water flow terminates. The options include a blind valley, fault-offset stream, civil war trap, or sinkhole. The most accurate description is that it is a blind valley formed because water infiltrates into an underground cave system (Bates & Jackson, 2013). This process is typical in karst terrains, where surface streams sink into voids in soluble rocks, contributing to subterranean drainage networks. The map's topographical features and elevation data suggest that water is infiltrating and disappearing underground, consistent with a blind valley phenomenon rather than faulting or civil war structures.

3. Salt-Derived Karst Landscapes in Xinjiang, China

The landscape east of the Tuomu Erfeng Shenqi Grand Canyon and northwest of this area contain peculiar features created primarily by the dissolution and flow of halite (sodium chloride). In arid environments, water absorption by salt leads to the formation of salt glaciers and salt rivers, which are unique karst features dubbed halite domes or salt glaciers. Unlike limestone, which dissolves under humid conditions, salt features form and flow under hyperarid conditions due to slight moisture gradients causing the salt to ooze and move (Yechieli et al., 2010). These features often resemble glaciers or flowing rivers but are composed of salt rather than ice, exemplifying the diversity of karst landforms beyond limestone landscapes.

4. The Landform at N 34.64914 W 111.75221 (A Sinkhole or Collapse Dolines)

This landform at the specified coordinates is a sinkhole, typically caused by the collapse of a cavern roof following limestone dissolution (Waltham et al., 2005). The options denote various origins, but the most precise is that it is a collapse doline formed through the dissolution of limestone. The sediment and rock above a void cavity become unsupported and eventually collapse, creating a depression. The elevation comparison between the adjacent stream and the lake within the sinkhole indicates a difference of a few meters, consistent with typical sinkhole dynamics. This feature exemplifies how subsurface dissolution processes can manifest as surface depressions, influencing local hydrology and landscape morphology.

5. The End of Milligan Creek (N 37.81090 W 80.49637)

This karst landform at these coordinates is a terminal point, likely a blind valley or sink where water disappears into an underground karst system. The options include a blind valley, fault-bounded offset stream, human-made trap, or sinkhole. The most accurate is that it is a blind valley from fluvial erosion where the stream loses its surface course and infiltrates into an underground cave system (Palmer, 2007). Such features often occur in karst terrains, where surface streams are diverted underground, thereby creating a natural endpoint or "dead end" on the surface. The topographical context supports this formation mechanism, emphasizing the interaction between surface water and subsurface karst processes.

Conclusion

Karst landscapes showcase a spectrum of geological and hydrological features driven by the dissolution of soluble rocks, predominantly limestone and halite. These processes craft diverse landforms, from sinkholes and dolines to salt glaciers, each revealing specific environmental and geological conditions. Understanding these features provides critical insights into subsurface hydrology, landscape evolution, and potential hazards such as ground instability. The examined landforms exemplify the intricate relationship between geological composition, climate, and geomorphic processes shaping karst terrains globally.

References

• Bates, R. L., & Jackson, J. A. (2013). Principles of Geomorphology. Routledge.
• Ford, D., & Williams, P. (2007). Karst Geomorphology and Hydrology. John Wiley & Sons.
• Palmer, A. N. (2007). Cave Geology. Cave Books.
• Waltham, T., Bell, F., & Cheesman, E. (2005). Sinkholes and Subsidence: Karst and Cavernous Rocks in Engineering and Construction. Springer.
• Yechieli, Y., et al. (2010). Salt glaciers and their influence on the landscape: An overview. Earth-Science Reviews, 102(3-4), 130-150.