In an unconformity between two layers of rock, how is the lower layer usually described? a. much older than the upper layer. b. much younger than the upper layer. c. the same age as the upper layer. d. a little younger than the upper layer

A. Much older than the upper layer.

An unconformity is a gap in age between two rock units. The upper unit is usually younger than the lower layer due to deposition of sediments in the lower layer due to erosion. Age gap between two layers of sediments or rocks depends upon how long the erosion took place and period in which  deposition of sediments stopped or ceased.

i believe you meant to say air rather than hair so the answer is below ")

the dead sea, the lowest place on earth at 430 metres (1,410 ft) below sea level, has a correspondingly high typical atmospheric pressure of 1065 hpa.