Ageologist notices that a river is eroding its valley at a constant rate. knowing the height of the valley walls, how could the geologist figure out when the river started carving the valley?
a.
count growth rings of trees growing on the valley floor.
b.
fill up the river valley with rocks, and time how long it takes the rocks to wash out.
c.
sit and observe the river for a few hours until the valley walls double in height.
d.
divide the height of the valley walls by the rate of erosion.

in addition to being able to metabolize, grow, digest food, and excrete wastes, what other functions must an organism perform if it is to survive? survival also depends on the ability to maintain one's boundaries, to move, to respond to stimuli, and to reproduce. oxygen is a survival need.

energy per photon is e = h*c / λ  

e = 6.63*10^-34 * 3*10^8 / 6*10^-7 j = 3.315*10^-19 j  

nr. of photons = 10j / 3.315*10 = ^-19 j per photon = 3.02*10^19 photons

1. glacier movement over the crust.

2. upwelling from the water table.

3. formation of a terminal moraine

explanation:

lakes can be formed as a result of these three options.