Final answer:
Hillside springs exist where the water table meets the surface, and water flows out due to natural slopes and gravity. Geological features like permeable rock layers, as well as processes such as soil creep, erosion, and sedimentation, play roles in spring formation. Additionally, events like volcanic eruptions and sinkhole formations can impact spring creation and existence.
Step-by-step explanation:
Hillside springs exist due to the intersection of the water table with the land surface, allowing ground water to flow out of the earth. This is often caused by geological formations such as permeable rock layers that allow water to be stored and then travel until it finds an exit at the hillside. Specifically, hills provide a natural pressure gradient due to gravity, which forces the water to move downhill until it reaches a point where it can emerge.
Various geological processes, such as soil creep, erosion, and sediment deposition, can alter the landscape and affect where and how hillside springs form. For instance, soil creep can affect the stability of slopes and the distribution of permeable layers, while erosion from water flow can create new paths for spring water to emerge. Moreover, sediment deposition can create aquifers that store water and feed these springs.
Historical events like volcanic eruptions, such as the one at Mount St. Helens, can drastically change the topography, leading to the formation or disruption of springs. Sinkholes, often a result of the dissolution of limestone by acidic groundwater, can also alter the underground pathways of water, potentially creating new springs or disrupting existing ones.