Complex sentence: Originally standing about in height, the platform mound itself was constructed in 10 stages, but extensive damage through erosion and amateur digging caused only the first four stages to have distinguishable form and purpose, while also decreasing the height of the mound to.
Split into simpler sentences: Originally standing about in height, the platform mound was constructed in 10 stages. Extensive damage through erosion and amateur digging have resulted in only the first four stages to have distinguishable form and purpose, while also decreasing the height of the mound to.