Elementary my dear Watson

This is a picture of the ground out where we park our car. There is little or no vegetation still attached to the soil, what vegetable matter there is is dry and piled in waves which are aligned across the slope. What can be deduced from this? 1) there has been a growth season which produced the vegetable matter. 2) That growth season finished and everything dried out. 3)there has been subsequent heavy rain enough to wash the plant litter into small rolls across the slope.