The worth of natural resources in contemporary economics is often based on renewable and exhaustible resources of the earth that is according to the worth of natural resources in contemporary economics. Renewable resources are resources that are used over and over again and can be replaced naturally. An example of this is water and oxygen. Nonrenewable resources are those that once they are used, they can not be reused again. An example is oil, once the oil is used, it does not resurface to be used again, instead, new oil is needed.