Geison

Geison (Greek: γεῖσον - often interchangeable with somewhat broader term Cornice) is an architectural term of relevance particularly to ancient Greek and Roman buildings, as well as archaeological publications of the same. The "geison" is the part of the entablature that projects outward from the top of the frieze in the Doric order and from the top of the frieze course (or sometimes architrave) of the Ionic and Corinthan orders; it forms the outer edge of the roof on the sides of a structure with a sloped roof. The upper edge of the exterior often had a drip edge formed as a hawksbeak moldingto shed water; there were also typically elaborate moldings or other decorative elements, sometimes painted. Above the "geison" ran the sima. The underside of the geison may be referred to as a soffit. The form of a "geison" (particularly the Hawksbeak molding of the outer edge) is often used as one element of the argument for the chronology of its building. [ The "geisa" of the Doric porch of Philo at Eleusis are labeled as γεῖσα Δωρικά (horizontal "geisa" with mutules) and γεῖσα Ἰωνικά (vertical "geisa" without mutules) - Robertson 382. ]

Horizontal "geison"

and water-spouts) ran above the horizontal geison along the sides of a building, acting as a rain gutter and final decoration.

Doric order

In the Doric order, the sloped underside of the horizontal "geison" is decorated with a series of protruding, rectangular mutules aligned with the triglyphs and metopes of the Doric frieze below. Each mutule typically had three rows of six "guttae" (decorative conical projections) protruding from its underside. The gaps between the mutules are termed "viae" (roads). The effect of this decoration was to thematically link the entire Doric entablature (architrave, frieze, and "geisa") with a repeating pattern of vertically and horizontally aligned architectural elements. Use of the hawksbill molding at the top of the projecting segment is common, as is the undercutting of the lower edge to aid in dispersing rainwater. In order to separate the "geison" from the frieze visually, there is typically a bed molding aligned with the face of the triglyphs.

Ionic and Corinthian orders

Horizontal "geisa" of these orders relied on moldings rather than the mutules of the Doric order for their decoration.

Raking "geison"

A raking "geison" ran along the top edge of a pediment, on a temple or other structure such as the "aedicula" of a "scaenae frons" (theater stage building). This element was typically less decorative than the horizontal "geison", and often of a differing profile from the horizontal "geison" of the same structure. The difference is particularly marked in the Doric order, where the raking "geison" lacks the distinctive mutules. The raking sima ran over the raking "geison" as a decorative finish and, essentially, a rain gutter.

References

*Robertson, D. S. 1943. Handbook of Greek and Roman Architecture 2nd Edition. Cambridge: Cambridge University Press

Notes