Why are albertas oil reserves so costly to obtain?

Hi Vada! They are costly to obtain because they are locked in shale rock. That makes them very difficult to get out. Hope that helps;)

Your answer is d. silli hope this ! : ) i left an explanation down below if you need it: a sill forms when hot magma squeezes between layers of rock to form a hardened sheet of rock. a sill is basically a tabular sheet intrusion between old layers of sedimentary rock, volcanic beds, or in the direction of foliation inherent in metamorphic rock. the word sill means a concordant intrusive sheet.