smith: for decades, geologist simon wilde has been climbing the jack hills in western australia, date stamping the rly earth. wilde: this is the famous discovery outcrop. this is the site where the world's oldest zircon crystals have been recorded. smith: though ancient, it's not the rocks themselves that are so old here, but the microscopic crystals of zircon within them. known in the gem trade as poor man's diamonds, zircon crystals form when molten rock cools in the earth's crust. and just like diamonds, zircons are forever. if you ever wanted to find a spot to ponder your oneness with the great age of the earth, you couldn't do better than this rock, because within it are the oldest remnants from the early earth ever found. older than you and i by a mere 4.4 billion years. at just a whisker younger than the age of the planet itself, this tiny treasure, zircon w74, is the ultimate aussie survivor. recycled from rock to rock, zircons like w74 have resisted everything the planet has thrown at them. and yet they've somehow managed to keep a diary of the earliest days locked deep withi

simon. >>> it is a little under two hours before the world cup match and usa is taking on belgium in a highly anticipated knockout around. no ties. no second chances. the fans are going wild. brian is live in salvador, brazil, with all of the excitement. brian? >> reporter: that's right. welcome to salvador, brazil. a beautiful coastal city. it's all about the biggest game for america right now. usa versus belgium in the knockout round. win or go home. let's set the stage here for a bit. we're out in front of the stadium. this is 50,000 people that will be in that stadium to watch today's big game. if you go to my left over here, you'll see fans that are over here at the bar that were watching argentina/switzerland game. a win by usa will send the team to the quarterfinals for just the third time in history and they'll play either argentina or switzerland in the next round on saturday. team usa will tell you this is the biggest game of their lives. >> guys need to make plays. it's going to take a couple special moments and i think that we have plenty of guys on our team that are very capable of creating those special moments. >> hopefully we don't play too tight. the mome