The "layers" are from an old ISO abstract classification which has been applied to how things really run in the physical world, often with the rhetorical equivalent of a sledgehammer. You should not try to follow layers as gospel, it will often lead to confusion.
SSL/TLS is a protocol which can be applied over a bidirectional data tunnel, and which provides a bidirectional data tunnel, with authentication (server by client, or mutual), confidentiality (through encryption) and verified integrity. In terms of "layers", it goes right between layer 4 and layer 6 of the OSI model, which shows that the concept of "layers" fails to capture the actual position of SSL/TLS.
It so happens that the authentication part of SSL/TLS (the "handshake") consists in a series of messages, which are exchanged in an alternate sequence; see the TLS specification, page 36, for a diagram showing that sequence. In "normal" SSL/TLS, the messages are exchanged over whatever bidirectional data tunnel SSL/TLS is applied on, usually a TCP connection. However, the cryptographic properties of the handshake come from the message contents, not from how they are sent. At that point, consider EAP: this is a framework for authentication protocols, consisting in messages; EAP is meant to be used over any transport mechanism which can send messages ("layer 2" if you really want to think about it in layers). Hence EAP-TLS has been defined: this is an authentication protocol, consisting in a sequence of messages which are the ones specified for the SSL/TLS handshake -- but sent as so many messages over the transport mechanism used by EAP. EAP-TLS is not TLS, it does not provide a tunnel for data; it is a protocol which reuses parts of the handshake which occurs at the beginning of a TLS connection.