Assume an underground mining cost of $25.5/ton ore for an orebody. assume open pit mining costs at $0.0028/kg ore removal and $0.0035/kg waste removal. determine the stripping ratio for an open operation that results in break-even cost differential between the two mining methods.

What first caused people to consider that the continents were once one large landmass?

1. crust 1 the metallic layer at the earth's center 2. inner core 3 the firm layer between the crust and the asthenosphere 3. lower mantle 2 the layer surrounding the inner core 4. asthenosphere 4 the semi-solid layer between the top layer and the upper mantle 5. upper mantle 5 the layer between the asthenosphere and lower mantle 6. top layer 6 the earth's outermost layer 7. outer core 7 the hottest part of the mantle

What can you learn about precipitation levels in south america from this map? brazil is experiencing a drought. it rains more in higher altitudes. peru received the highest level of rain. venezuela got less than 25 cm of rain.