Explain why shorelines are always changing

They are always changing due to the effects of erosion and weathering.

Erosion:

- Attrition - rocks smashing into each other and breaking down becoming smaller and smoother

- Solution - soluble particles dissolving

- Abrasion - rocks that are in the sea wearing down the sea bed (although this isn't very common)

- Hydraulic Action - when there are cracks in the cliffs, water can push air into them which creates pressure causing the cracks to get bigger

Deposition:

- Sediments get deposited onto the beaches and other areas, thus adding to the shoreline

Weathering:

- Physical: temperature, wind, rain, waves, freeze-thaw

- Biological: by plants and/or animals

- Chemical: acidic rain

Hope this is what you wanted and I hope it helps. :)