there's a place called la brea tar pits, and you may have smelt it, that is methane gas.ides the smell it's a gold mine for scientists. the fossils they are uncovering in the area are unlike any other place in north america, and they are uncovering mysteries of the past and giving us an idea of our global warming future. it's all from digging out a subway in l.a. let's check it out. [ ♪ music ] . >> reporter: it's called the miracle mile, a stretch of los angeles defined by deco cool and modern museums. now its future is defining it's prehistory orric past. >> we've gone down 70 feet, 330,000 years. >> from the sub way to the sea - a treasure trove of ancient goodies has been uncovered, proving the sea was here. >> 300,000 years ago this was all ocean, and it had flooded a forest and it was cool and it was nice - much nicer than 100 degrees today >>> jim scott is the palliantologist on the site. >> these fossils are 180 years old. there's a lot of cold water clams. on the right is a gooey duck and washington clams - we have them off the coast of california, but further no