Foliated rocks are formed under a great amount of relatively equal pressure, where as non-foliated rocks are formed under high temperatures.
Non-foliated rocks, however, lack this visual characteristic. See the image below.
The reason for this is actually pretty intuitive. Foliated look like they’ve been “smashed” together for a reason: they have been. In the case of these rocks, they have been under a great amount of pressure. Each metamorphic rock has a “parent,” called a protolith. It’s the protolith that has undergone metamorphosis.
Save your time - order a paper!
Get your paper written from scratch within the tight deadline. Our service is a reliable solution to all your troubles. Place an order on any task and we will take care of it. You won’t have to worry about the quality and deadlinesOrder Paper Now
On the contrary, non-foliated metamorphic rocks aren’t subject to the same degree of pressure. The amount of pressure that a non-foliated rock has pressed upon it could, in fact, equal the amount of pressure that the foliated rock had, but it’s an unequal pressure, so it doesn’t have the sandwich-type aesthetic. The key force behind the creation of the non-foliated rock is temperature.