Final answer:
Spirals on an Ionic capital are called volutes, and they distinguish Ionic capitals from Doric and Corinthian styles. Doric capitals have a simple design, while Corinthian capitals are known for their acanthus leaves.
Step-by-step explanation:
The spirals in an Ionic capital are called volutes. These ornaments are shaped like scrolls or cinnamon rolls and are prominently featured on Ionic capitals. When observing an Ionic capital, which depicts the north porch of the Erechtheion, the volutes are a distinctive aspect that marks this style of architecture, differentiating it from the simpler Doric and more elaborate Corinthian orders.
The Corinthian capital, on the other hand, is recognized for its use of acanthus leaves, as opposed to the Ionic volutes. It is often seen as more ornate, and Roman architects particularly favored it, utilizing it in many notable buildings such as the Temple of Mars Ultor and the Pantheon. Comparatively, the Doric columns are much simpler with unadorned square abaci and no volutes.
Understanding these characteristics is essential for distinguishing among the three classical orders of ancient Greek and Roman architecture. The visual differences are key to identifying Ionic, Doric, and Corinthian columns in various historical structures.