JULES MARCOU 115 



Vinci. He never learned to speak English easily, to make it a 

 second mother tongue as Agassiz did, and at that time his use 

 of the language was most imperfect. Partly because I well 

 understood him in French, but rather because of our common 

 interest in geology, we soon came together and were long near 

 friends. He was the first real geologist with whom I had a chance 

 to take the field, and from him in 1860 in a prolonged excur- 

 sion to Gay Head on Martha's Vineyard, I had my first lesson 

 in actual exploration under the eyes of a trained man. Unfor- 

 tunately, Marcou, though versed in the identification of hori- 

 zons, had no sense of structural geology; so I was in no wise 

 helped in the task of unravelling the complicated tangle of 

 greatly disturbed strata which is there exhibited. In his opin- 

 ion the folds and faults which are evident in the outcrop were 

 altogether due to the slipping of the beds. Though these land- 

 slide movements have evidently had some effect in producing 

 the tangle, I saw at the end of a week of work that this 

 effect was but slight, and that other influences had been the 

 main source of the complexity. This was my first piece of 

 interpretation; it brought me no further than the stage of 

 drilling, yet it was most profitable. Nearly thirty years after- 

 ward, on returning to the inquiry and setting about it with 

 deliberation, the problem was solved. 



I made a number of other shorter journeys with Marcou, all 

 in the neighborhood of Boston. On these I learned from him 

 more of the traditions of field work as he had received them 

 from the various experts with whom he had been in contact. 

 Yet he was little skilled in solving the riddles of geological 

 structures and entirely inattentive to the meaning of physio- 

 graphic forms. But as in that day few cared for those problems 

 I was left to my own devices. I puzzled out some things in the 

 structure of the Boston Basin by much footing over the ground 

 and plotting sections and the dips of the strata; but it was 

 years after, when I had a chance of help from the Swiss field 

 workers, before I obtained any command of the methods I 



