This one hour video is the first part of a three part BBC series (2010) called Men of Rock .
The first half is about James Hutton and his geological observations in the second half of the 18th century that supported his idea th at the Earth is so old that it has "no vestige of a beginning,– no prospect of an end." https://www.youtube.com/watch?v=bakeXEdlXXc The narrotor, Iain Stewart, is a geologist and his enthusiasm for the subject makes you want to become geologist. In the second half of the video he talks about Lord Kelvin who did not like the idea that the Earth had no beginning because that implied geological change was powered by a perpetual heat engine. According to the laws of thermodynamics (which Kelvin helped to formulate) the Earth had to have a beginning even if it was much older than the creation date of 4004 BC as found in the Bible. Kelvin assumed the Earth began as molten ball of rock and estimated the age of Earth in terms of how long it would take the molten ball to cool. His calculated the Earth took 20 to 40 million years to cool. This is 4 minute video descriees one of Hutton's seminal discoverys of a geological "uncomformity" at Siccar Point in Scotland. https://www.youtube.com/watch?v=oQzmfcUKSFM Harry