Question

in the following figure, determine the correct sequence from oldest to youngest:

cambrian
g muav limestone
h bright angel shale
i tapeats sandstone
a nankoweap group
chuar shales
b dox sandstone
c shinumo quartzite
d hakatai shale
pre - cambrian
l
m
e
igneous sill
f
gravel
s
zoroaster granite
j
bass dolomite
r
vishnu schist
k
grand canyon inner gorge

d - c - h - m
b - e - r - g
e - j - c - f
k - s - f - i

Explanation:

Step1: Apply law of superposition

In undisturbed sedimentary rock layers, the oldest layer is at the bottom and the youngest is at the top. Also, intrusive rocks are younger than the rocks they intrude.

Step2: Evaluate each option

• Option D - C - H - M: D and C are Precambrian layers, H is a Cambrian layer. M (an igneous sill) is younger than the layers it intrudes. This sequence is incorrect as it doesn't follow the correct age - order.
• Option B - E - R - G: B and E are Precambrian layers, R is an unconformity surface, and G is a Cambrian layer. But the order is incorrect as the unconformity R is not in the right position relative to the layers based on age.
• Option E - J - C - F: E is a Precambrian layer, J (Zoroaster Granite) is an intrusive rock that intrudes into Precambrian rocks, C is a Precambrian layer above the intrusion level, and F (an igneous dike) is younger than the rocks it cuts through. This sequence is incorrect.
• Option K - S - F - I: K (Vishnu Schist) is one of the oldest rocks in the Grand Canyon, S (Gravel) is deposited on top of older rocks, F (igneous dike) intrudes into S and older rocks, and I (Tapeats Sandstone) is a Cambrian layer which is younger than the underlying rocks. This sequence follows the principle of superposition and cross - cutting relationships correctly.

Answer:

K-S-F-I