In contrast , dirt , sand , and rocks have lower heat capacities ( 0.19 to 0.35 J g K ) .
Heat capacities can only transmit heat into the earth by conduction and not by convection .
In contrast , dirt , sand , and rocks have lower heat capacities ( 0.19 to 0.35 J g K ) , and they can only transmit heat into the earth by conduction and not by convection .