Answer:
arrowhead : 15
bone : 721
clay bowl : 0
necklace : 462
woven basket : -1200
Step-by-step explanation:
Consider sea level to be zero elevation, then anything above sea level is related to a positive number equal he elevation at which it was found, and anything below sea level would be associated with a negative number (the opposite of the depth at which it was found,as shown below:
arrowhead : 15
bone : 721
clay bowl : 0
necklace : 462
woven basket : -1200