What was the “Cambrian explosion”?

Mexico city is an example of how humans alter their environment because it was a. one of the world’s largest cities b. built on drained and filled lake beds c. built after conquest by the spanish d. once the capital of the aztec empire

Identify the type of weathering seen in each picture ? chemical weathering mechanical weathering

Which is an accurate description of the physical characteristics of poland? its fertile soil is found only along riverbanks, and its mountainous region in the northwest has few mineral resources. it is mostly flat with fertile soil except in the east and northeast, and the mountainous region in the south has large deposits of coal and copper. it is covered with thick forests, and it has large reserves of coal, petroleum, and natural gas. its landscape is dominated by plateaus, mountains, and high ridges, and it has large deposits of sulfur and copper in the northeast.