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.

small, big, or no change could occur in the phenotype. it could cause something as simple as a cats ears to curl backwards or something as frighting as death. it could also occur in the protien-coding area and have an effect on that but no effect on the amino acids. what has to occur is a changing in the hox gene or the control gene.

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]