If sinkhole topography is related to the underground erosion of rock which results in cavities, what typeof rock formations would be considered most susceptible to having the condition develop?

it is correct? a=4.8?

Stop D: The High Level LRT bridge section (UTM 333280 5934116, NAD 83) Immediately west of the LRT bridge is an small cliff in which are displayed 6-7 m of fine-grained sediment that shows almost horizontal layers, believed to have formed in the last 8000 years. The exposure is parallel to the river, and is preserved from erosion and is accessible because and engineered berm has been constructed between the section and the river. At the top of the section one can see the remnants of a brickyard that operated at the site between 1898 and 1913. A huge flood destroyed the yard in 1915, giving a good impression of the magnitude of peak historic flooding and flows. Within the lower third of the cliff there is a conspicuous whitish layer, and several brown to red layers. Grains in the whitish layer have been dated using isotopes to between 7584- 7682 years before present. This age coincides with the eruption of Mount Mazama, a huge volcano that existed on the site of Crater Lake, Oregon.…

A 15m wide and 15m high 30m long underground storage facility is excavated in a massive limestone rock mass (with few random long joints). The long axis of the excavation oriented N50°W. Traces of two major joint sets are identified as following: Joint A: plunge of trace of the joint on east wall is 29°S; trend of the line of intersection of the joint on the roof is 20°. Joint B: plunge of trace of the joint on east wall is 36°N; trend of the line of intersection with the roof is 286°.