Which geologic principle is the reason rock layers typically form parallel to each other?

The phylogenetic tree illustrates the relationship between humans and our closest living relatives. the tree was based on biochemical comparisons, including dna and amino acid sequences. according to the biomolecular data, we could infer that

Most crimes involve some evidence relating to the human body; for that reason, what related science is frequently used in forensic investigations? a)psychiatry b)physics c)botany d)biology

Why does the earth spin slowly, not faster? is it possible to prove it scientifically? can you prove it with math?