Energy pyramids show the amount of available chemical energy available at each trophic level (feeding level) of a food chain. During life processes about ___ of the energy from the food chain is converted to heat and used for life processes, while about is transferred to other organisms in the next level of the food chain. Choose the two numbers that would go in the blank

What did hunter gathers do to alter the environment?

Which statement describes the punctuated equilibrium theory?

Match each law or principle to its description. 1. law of original horizontality sediment continues to spread in a flat plane until it hits an edge or runs out of material. 2. law of superposition the youngest strata are at the top and the oldest are at the bottom. 3. law of original lateral continuity sediment gets pulled down by gravity in a horizontal and flat layer. 4. law of cross-cutting or intrusive relationships if there is a fracture or intrusive feature seen in rock strata, it is younger than the rock strata.