The word metamorphic means changed , so rocks that have changed are called metamorphic rocks.
{"Image DocumentName": "The word metamorphic means changed , so rocks that have changed are called metamorphic rocks.", "Image ImageDescription": "Layers of sedimentary rocks are changed by underground heat or underground weight, or both. They have a layered or streaky appearance. When limestone is heated and compressed it forms marble. Sandstone changes into a much harder rock called quartzite.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}