The Map That Changed the World by Simon Winchester

The Map That Changed the World: William Smith and the Birth of Modern Geology by Simon Winchester


This book is a biography of William Smith, an Englishman who founded the science of geology two hundred years ago. Much of this book is filled with local color and history. People had studied rocks before, but Smith added the dimension of time. The depth at which a rock is found tells us the time in the past when it was created.

Canals and Coal

Canals became important in the late 18th century in England. They greatly reduced the cost of transporting coal, and so fueled the Industrial Revolution. Canals had the advantage over roads that the transit was much smoother and fragile goods were much less likely to break. The best route for a canal depended upon the kinds of rock (hard or soft) that needed to be excavated, and whether the remaining rocks would absorb water.


William Smith was the son of a farmer. He did not seek the profession of scientist. It happened because of his work as a surveyor for the digging of canals in England. While digging, he made some important observations. He noticed that different strata (layers) appeared in the same vertical order at different geographical locations. The thickness of strata varied but not the order. He surmised that each layer (stratum) was not just a local phenomenon, but one that extended throughout much of the country. For example, at one location, the order from top to bottom was: Sandstone, Siltstone, Mudstone, Nonmarine Band, Marine Band, Coal, and Seat Earth. Each strata was layed down at a particular time in the distant past. Smith drew maps of the layers, with a different color for each stratum, showing its geographical extent.

Matching Strata from Different Sites

Most importantly, when deciding whether two strata from different geographical locations were equivalent, Smith considered not only the rock chemistry (grain size, color, reaction to acid), but also the rock biology, what kinds of fossils were in the rock. For example, two strata of limestone were not equivalent, unless they contained the same kinds of fossils (bivalves, ammonites, gastropods, corals).

Gaining Recognition

Much of the book is about the troubles he had getting recognition for his discovery, due to the fact that science was dominated by the upper class, while he was of the lower class. But being of the lower class had the advantage that he worked with his hands, while the upper class sat in their fancy drawing rooms having abstract philosophical discussions unrelated to reality. The author bemoans the fact that Smith had many financial problems. But Smith made a good living surveying for canals and draining swamps. His problem was that he spent too much money, especially for expensive residences in London from which to entertain important guests.