Blockchain blocks? 
Is there a problem with my terminology? Probably. I've been looking into this stuff for just a day and a bit. I have not yet grokked how it all works together.
The reason I asked that was that there is no data in the bitcoin blockchain relating to the exchange rate. When bitcoins are traded for fiat, they are either done at an exchange, or in-person / face-to-face. But generally, the exchange rate from the largest market (the BTC/USD at Mt. Gox) suffices for a record of price history.