Simplify the following text for a Grade 7 native English-speaking person.
Original: As with most river and creek valleys in south-eastern Australia , the natural landscape of Araluen Creek and its valley were completely destroyed by rampant and extremely destructive gold mining during the ` gold rush ' in the latter half of the 19th century .
Simplified: The natural shape and look of Araluen Creek and its valley were completely destroyed by uncontrolled and very destructive gold mining . This took place during the ` gold rush ' in the second half of the 1800s .