2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
rich gave them, but the brachiopods include Chazy forms with related Black 
River and Trenton types. 
BACKGROUND FOR THE STUDIES 
In 1939, I had my first introduction to the Appalachians with Dr. Charles 
Butts and Dr. Josiah Bridge. Dr. Butts, who knew the Appalachians more inti- 
mately than anyone before him, kindly consented to show Bridge and myself 
their intricacies from Pratt Ferry in Alabama, where the Appalachian structures 
plunge under the Coastal Plain, to Winchester, Va. We saw the facies changes 
involving the Athens and Arline formations and the reefs of the Effna at Porter- 
field Quarry. This first expedition was followed by others, many of them with 
Dr. B. N. Cooper. 
My association with Dr. B. N. Cooper began about 1941 when the latter called 
at the National Museum to confer regarding some of his fossils from Virginia. 
Cooper was then studying the Ordovician sequences to learn of deposits of chemi- 
cal limestone. These studies had made him familiar with many interesting and 
important sections. The conference resulted in the discovery that the two of us 
independently had arrived at the same facies picture for the Middle Ordovician 
stratigraphy in the Appalachians of Virginia. It was then decided to join forces 
and apply the new ideas to the sequences southwest of Virginia in Tennessee, 
Georgia, and Alabama. We made seven expeditions between 1941 and 1951. 
Additional background was obtained in several expeditions to the Arbuckle 
Mountains, and two expeditions to the Antelope Valley of Nevada where an in- 
comparable Ordovician sequence is exposed. Dr. Bridge and I visited Chazy in 
1938 to study the typical sequences along Lake Champlain. Alwyn Williams of 
Wales and I examined numerous sections in central Pennsylvania, covering the 
ground described by G. M. Kay. The same party examined sections in southern 
Wisconsin, Minnesota, and Iowa. All these expeditions added to our knowledge 
and increased the collections. 
BUILDING THE COLLECTION 
The collection on which this study is based is a large one and was derived 
from many sources. The initial stages of building consisted of selecting good 
specimens from the large mass of stratigraphic material obtained by various mem- 
bers of the U. S. Geological Survey. Part of this material was collected by E. O. 
Ulrich, and another large part was brought in by Charles Butts during his years 
of mapping in the Appalachians. Other contributors were R. S. Bassler, G. W. 
Stose, Josiah Bridge, and Edwin Kirk. 
The largest part of the collection was obtained by me in various trips to the 
Appalachians and the West. Each year specific localities of promise were visited 
and revisited and rare fossils tracked down so that adequate material for de- 
scription was finally brought together. It was mainly through my efforts that 
much silicified material was brought in, and later processed. It was this material 
