76 Charles Schuchert — Historical Geology, 1818-1918. 



series of letters to Billings that the Taconic fossils are 

 like those of his Primordial system, or what we now call 

 the Middle Cambrian (31, 210, 1861, et seq.). 



In a series of articles published by S. W. Ford in the 

 Journal between 1871 and 1886, there was developed the 

 further new fact that in Rensselaer and Columbia coun- 

 ties, New York, the so-called Hudson River group 

 abounds in " Primordial' ' fossils wholly unlike those of 

 the Potsdam, and which Ford later on spoke of as 

 belonging to "Lower Potsdam" time. 



James D. Dana entered the field of the Taconic area in 

 1871 and demonstrated that the system also abounds in 

 Ordovician fossiliferous formations. Then came the 

 far-reaching work of Charles D. Walcott, beginning in 

 1886, which showed that all through eastern New York 

 and into northern Vermont the Hudson River group and 

 the Taconic system abound not only in Ordovician but 

 also in Cambrian fossils. Finally in 1888 Dana pre- 

 sented a Brief History of Taconic Ideas, and laid away 

 the system with these words (36, 27) : 



"It is almost fifty years since the Taconic system made its 

 abrupt entrance into geological science. Notwithstanding some 

 good points, it has been through its greater errors, long a hin- 

 drance to progress here and abroad . . . Bnt, whether the evil 

 or the good has predominated, we may now hope, while heartily 

 honoring Professor Emmons for his earnest geological labors and 

 his discoveries, that Taconic ideas may be allowed to be and 

 remain part of the past." 



As an epitaph Dana placed over the remains of the 

 Taconic system the black-faced numerals 1841-1888, 

 That the remains of the system, however, and the term 

 Taconic are still alive and demanding a rehearing is 

 apparent to all interested stratigraphers. This is not 

 the place to set the matter right, and all that can be done 

 at the present time is to point out what are the things 

 that still keep alive Emmons's system. 



In the typical area of the Taconic system, i. e., in Rens- 

 selaer County, Emmons in 1844-1846 produced the fossils 

 At ops trilineatus and Elliptocephala asaphoides. S. W. 

 Ford, as stated above, later produced from the same gen- 

 eral area many other fossils that he demonstrated to be 

 older than the Potsdam sandstone. To this time he gave 

 the name of Lower Potsdam, thus proving on paleon- 

 tological grounds that at least some part of the Taconic 



