Final answer:
The deep concave molding between two fillets, known as trochilus, is called a Scotia. It enhances the depth and visual interest of architectural structures, especially in classical architecture around the bases of columns.
Step-by-step explanation:
The term you are looking for that describes a deep concave molding between two fillets, also known as trochilus, is a) Scotia. This molding, often found in classical architecture, creates a shadow effect that enhances the depth and visual interest of a structure. The molding is part of an architectural feature where the curving profile resembles a smooth, concave surface nestled between two raised bands (fillets). This decorative element can be seen in ancient structures and is often associated with the bases of columns.
For example, the Doric columns, known for their simple, unadorned square abacus and a flared echinus, could be accompanied by a scotia in more elaborate base designs. The scotia could add to the play of light and shadow on the structure, enhancing the visual complexity of the column's base. Furthermore, deep incising and cut surfaces, as mentioned by Beth discussing church decoration, indicates the importance of shadow in classical and later architecture. Indeed, decorative elements like the scotia were sometimes painted to emphasize their depth and artistry.