Notice the formation of the indentations and their subsequent branching; and also that holes form in the skin from which branchings also proceed.
"Liquid Drops and Globules, their Formation and Movements"
Chas. R. Darling
All the ridges have deep indentations through which the cold air, as well as the streams, descends to the plain.
"The South of France--East Half"
Charles Bertram Black
Digging their nails into the indentations, the dogs followed.
"The Eternal Maiden"
T. Everett Harré