Robert sent in these links which have an interesting take on Velikovsky, who had amassed a lot of interested from students of the period.
https://archive.org/details/vkvbd
https://www.velikovsky.info/horizon-worlds-in-collision/ .. but has disappeared from this one … https://archive.org/detals/wrldsc
As Velikovsky considered Mars played a role in his Worlds in Collision drama we may take note of a link sent in by Gary at www.dailymail.co.uk/sciencetech/article-9087871/ … NASAs robotic lander is equipped with some remarkable gadgets and instruments. It has an impressive number of tasks to perform. One of these is a seismometer that has been used to count up Marsquakes. These are mostly very small tremors but collectively they have allowed some interesting information to be gleaned. The make-up of Mars into three layers – a core, mantle and crust. Somewhat like the earth you might think but on Mars the crust is 23 miles thick. On the ocean bottom of the earth the crust is just 3 miles thick, it is thought, but gets thicker beneath the continents – up to 18 miles and not too far away from Mars.