In 1881, he published The Physics of the Earth’s Crust, in which he postulated a non-homogenous composition of the Earth. He speculated that the crust may sit atop a liquid layer. This was the most prominent work on the topic since Alexander von Humboldt, but it went largely ignored until the work of Alfred Wegener. Much of his work into continental drift was ridiculed, as other geologists of the time clung to Solid State Theory. However, Fisher's observations were based on careful scientific deductions rather than speculation.