What kind of erosion has helped paleontologists and geologists study the rock layers in the Badlands National Park? Chemical erosion causing hydration causing rocks to break up and ways away.

The mechanical forces of wind, water and freezing wore away the layers of rock.

A combination of chemical and biological erosion wore away layers of rock.

Biological weathering from lichen and bacteria colonies ate away at the rock layers.

Largely uneconomic because they provide little profit or food surplusi think so

The answer to this is a

As someone who have lived in northern moravia at industrial steel and coal city of ostrava, the closest point is b), but it is questionable. i am not sure how to compare efficiency of largest steel mill in czech republic in comparison to china which is the biggest exporter, but czech steel factories were modernized and run more efficient that 25-35 years ago, and been privatized and owned by mittal. the workforce had been shrinking, so not exactly sure what that c is pointing to (aging of workforce, size of it, or quality). northern moravia is a part of larger coal basin that extend to poland with large coal deposits. this was foundation for the steel industry in the 1800's together with large ore deposits that was mined in proximity of the beskidy mountains less than 25 miles from ostrava. the iron ore mines had been depleted for several decades, and since the late 70's when communists run the country, they were already importing soviet iron ore. coal mining within city of ostrava cased to exist in the 1990's due environmental issues, and also cost. the mines were getting deeper and more costly to operate and there is no more mining within ostrava. couple mines are still in operation in karvina county which is next to ostrava. currently the coal deposits south of the city were not opened due environmental issue which would mean destruction of third largest mountain range in the country. therefore, my conclusion is is b, as the ore and coal resources been shrinking. the biggest challenge not mentioned here is of course competition from russia, ukraine, and china, which can produce steel much cheaper.