Due to demand form users as reported by Bittrex, the popular crypto currency exchange has opened an Ethereum Classic (ETC) market - BTC/ETC trading pair. Bittrex users will be credited the amount of ETC that they had in Bittrex in the form of Ethereum (ETH) at the time of the hard fork and be able to generate a separate Ethereum Classic deposit address.
Note that due to the current replay attacks occurring against both chains and potential of future cross chain attacks, Bittrex WILL NOT be crediting you if you deposit ETC to an ETH deposit address or vice versa. Please make sure you are depositing on the proper chain.