How much traces lasting a million years would human civilization leave after perishing?

Question

While there is a nice webcomic with a similar theme, I'm talking about a hopefully more reliable claim: The Science of Discworld alternates between chapters written by fantasy author Terry Pratchett about the fantasy setting of the Discworld's wizards having (accidentally) created Earth inside a glass bowl and observing its evolution fast forwarded, and chapters written by mathematician Ian Stewart and biologist Jack Cohen trying to elaborate on the scientific part of the respective epoch.

Now while one of the fantasy chapters describes a pre-human (in fact, some large lizards, you know, dinosaurs) civilization that is then extinguished by a meteor (and was made-up for all we know), the following scientific chapter states the following (bold emphasis mine):

In order not to mislead you, we should point out at once that there is no scientific evidence for the existence of any dinosaur civ­ilization, no matter what events are going on in the Roundworld Project. But... whenever a scientist says 'there is no scientific evi­dence for', there are three important questions you should ask -especially if it's a government scientist. These are: 'Is there any evi­dence against?, 'Has anyone looked?', and 'If they did, would they expect to find anything?'

The answers here are 'no,' 'no', and 'no'. Deep Time hides a lot, especially when it's assisted by continental movement, the bulldoz­ing ice sheets, volcanic action and the occasional doomed asteroid. There are few surviving human artefacts more than ten thousand years old, and if we died out today, the only evidence of our civi­lization that might survive for a million years would be a few dead probes in deep space and various bits of debris on the Moon. Sixty-five million? Not a chance. So although a dinosaurian civilization is pure fantasy, or, rather, pure speculation, we can't rule it out absolutely. As for dinosaurs who were sufficiently advanced to use tools, herd other dinosaurs ... well, Deep Time would wash over them without a ripple.

So, is that true? Would the civilization of mankind, once perished for a million years, leave no traces more noticeable than the dinosaurs' bones are to us nowadays?

Answer 1

The concept of the "anthropocene" answers your question.

See

• Wikipedia — The Anthropocene
• Quirks and Quarks — The Anthropocene: The epoch of humans

The term was coined "because a growing number of geologists think that human activity is having such an impact on our world that we're inaugurating a new geological interval. It's signature will be detectable many millions of years from now." (Quirks and Quarks)

Proposed marks we'll leave in the geological record:

• A "building" strata: the materials that makes up our cities will add an identifiable strata to the record in the right parts of Earth (Quirks)
• Sea level increases will cover red soils with black mud (Quirks)
• Changes to the isotopic composition of soils reflecting environmental change (Quirks)
• Plastic (Quirks)
• Biostratigraphic changes: changes in distributions of animal fossils due to climate-caused migration, extinctions, and physical translocation of species by humans
• Increased acidity in the oceans will cause reef coral deaths, and will dissolve away lime sediments (this type of effect is quite clear in previous global warming periods) (Quirks)

The impact that humanity has had is geologically quite abrupt, and may be difficult to distinguish from a meteorite impact. (Quirks)