It’s also important to note what it talks about in chapter 5.4 on page 94. Not only was the water they encountered unexpected but also that amount of heat. As you mentioned they had to stop drilling, ultimately at 7.6 miles, which at that high of a temp at that shallow of a depth using their magma theory thermal gradient, with the heat source coming from the earths core, would put the temperature of our earth’s core at over 350,000 degrees! Thousands of times hotter than the surface of the sun! An interior that hot does not work for any theory! It got way too hot way too fast, according to the magma centered theory. But taking into account what Jacob said, if the heat source is in the crust itself via frictional heating, it makes sense. It also makes sense why sometimes they drill and find cooler temps, like when they drilled in Long Valley CA. Less frictional heating, less heat.