Exploration and production during the Pioneering Epoch was onshore, where in fact most of the world s oil lies. It began with very primitive technology and understanding, but progress was remarkably rapid. The rotary rig was introduced to replace the cable tool; well logging was developed to identify the formations and their oil content; and seismic surveys were brought into wide use to investigate geological structure at depth. All were established well before the end of the epoch.

It was the great age of field geology. Pioneering geologists on foot and muleback scoured the world for prospects, working under often arduous conditions far from base ^[37]. They had to be men of initiative, as well as rugged individualists. They searched, first, for seepages, and then for promising structures in the vicinity. But most of all they looked at the rocks to see if they had the essential characteristics and structural style to make an oil province. They developed a nose for what worked and what did not, and they mainly got it right. Kingston ^[38] describes how Esso had a small group of such explorers that roamed the world from 1940 to 1960, searching out every nook and cranny. He comments on the ending of this chapter:

The field studies and overseas travel came to an end, and the roving assignments ceased [in response to the move offshore]. During the 1970s and early 1980s, the price of oil rose significantly, and the oil industry went on an...