Sentence 1: The bulldozer had done a great job. 
 Sentence 3: His crew began slowly moving away the larger chunks of rock 
 Sentence 4:  They were mindful to look for any bits of large bone 
 Sentence 5:  What they found surprised them 
 Option 1: It had smashed through the building with no problem. 
 Option 2: It had smashed through the soil and sediment with no problem.