Precisely how to reconstruct the planetary past is not predetermined. This article compares three contemporary plans, dreamed up in the United States during the Interwar and Depression years, that deploy diverse techniques to evoke extinct environments. Building on Martin Rudwick's historicization of ‘scenes from deep time’, this article develops the concept of designs on deep time to explain how public displays of the planetary past circulate anything-but-neutral ideas about past and present to awed audiences. By detailing three contemporary designs on deep time—Pleistocene Park at the La Brea Tar Pits, a sensational World's Fair exhibit called ‘The World a Million Years Ago’, and a dinosaur park where living fossils and ancient plants approximated a Mesozoic atmosphere—this article captures diverse philosophies about how to construct persuasive encounters with the prehistoric past. It also demonstrates how, despite disparate approaches, these designers of deep time displays all used the planetary past to legitimate present regimes and foster faith in human progress. During the 1920s and 1930s, when the wounds of war, changing demographics, and economic depression collaborated to dispute a prevailing myth of American progress, deep time by design buoyed faith in a better future.

确切地说，如何重建行星的过去并不是预先确定的。本文比较了美国在两次世界大战和经济大萧条时期提出的三个当代计划，它们部署了多种技术来唤起灭绝的环境。基于 Martin Rudwick 对“深时场景”的历史化，本文发展了深时设计的概念，以解释行星过去的公开展示如何向敬畏的观众传播关于过去和现在的绝非中立的想法。通过详细介绍三个关于深度时间的当代设计——位于拉布雷亚沥青坑的更新世公园，一个轰动一时的世界博览会展览，名为“一百万年前的世界”，和一个恐龙公园，那里的活化石和古老的植物近似于中生代的大气层——这篇文章捕捉了关于如何与史前过去建立有说服力的相遇的不同哲学。它还展示了，尽管采用了不同的方法，这些深度时间显示的设计者如何都利用行星的过去来使当前的制度合法化，并培养对人类进步的信念。在 1920 年代和 1930 年代，当战争的创伤、不断变化的人口结构和经济萧条共同对美国进步的一个普遍神话提出质疑时，设计的深度时间激发了人们对更美好未来的信心。