Complex sentence: The stepwell was later flooded by the nearby Saraswati river and silted over until the late 1980s, when it was excavated by the Archeological Survey of India, with the carvings found in pristine condition.
Split into simpler sentences: The stepwell was later flooded by the nearby Saraswati River and silted over until the late 1980s. When it was excavated by the Archeological Survey of India, the carvings were found in pristine condition.