It's difficult to know exactly what you mean by "melting plates" without more context. Could you please clarify what you're referring to?

Here are some possibilities and what they might melt into:

* Metal plates: These could be made of various metals like steel, aluminum, or copper. Melting them would result in liquid metal.

* Plastic plates: These are often made from polypropylene or polystyrene. Melting them would produce a viscous liquid that could be used to make other plastic products.

* Ceramic plates: These are typically made from clay. Melting them would result in a glassy substance.

* Geological tectonic plates: These are large slabs of Earth's crust. While they don't melt completely, their movement and interactions can cause magma to rise from the mantle, leading to volcanic eruptions.

Please provide more information about the type of plates you're asking about, and I'll be happy to give you a more specific answer.