R. L. Moodie — Mason Creek Shales. 281 



30 ; Twp. 33 ; Range 8 ; the land now being owned by Mrs. 

 Emma Akerly of Wilmington, Illinois. 



The fossil-bearing nodules occur throughout six to eight feet 

 of shale, just above the coal, along both banks of the creek at 

 the " upper beds," as the Bartlett place is called. They may 

 be also seen in the creek bed, when the water is low, still 

 embedded in the shale. With a common potato fork the shale 

 is easily turned and the nodules come out for all the world like 

 potatoes. Once in a while " pockets " are struck from which 

 one may secure a peck or more of nodules. Nearly every 

 nodnle has a fossil at the " upper beds " but all of the fossils are 

 not well preserved, possibly only one or two out of every 

 eight or ten being worth carrying to the museum. The stream 

 bed at the Bartlett place is filled with glacial bowlders (fig. 2) 

 which form an excellent base on which to crack the nodules. 

 The nodules crack best when wet and it requires some skill 

 and practice to crack them evenly. The nodules vary in shape 

 and form from perfectly round ones, one-half an inch in 

 diameter, to oval, elongate ones 17 inches or more in length. 

 Many are quite irregular and it is soon noticed that the irregu- 

 lar nodules seldom have good fossils, often none at all. The 

 nodules seem quite light, and in one place, where the stream 

 curves, they are piled in a long windrow. On this pile were 

 found several good specimens of Crustacea and many good 

 plants, in nodules cracked open by the frost. 



The fossils at the " upper beds " are localized into special 

 strata. At one place in the upper part of the deposit in a red- 

 dish shale one finds that insects are more abundant than they 

 are lower down. The Crustacea appear to come from a definite 

 locality in apparently the same shale. At the lower end of the 

 deposits certain definite species of Pecopteris are localized. It 

 is an interesting fact that one seldom finds a Neuropteris at 

 the "upper beds.'* The most abundant fossils are various species 

 of Pecopteris and Annularia. When specimens of Neurop- 

 teris are found they are usually discovered at the lower end of 

 the exposures. In one place behind the "island" very blue 

 nodules, hard and flinty, with sometimes well-preserved fronds 

 of Pecopteris, are found quite definitely localized. These 

 nodules are more likely to assume an irregular shape. These 

 localizations of the various species of fossils are, of course, 

 what we would expect from our knowledge of the manner in 

 which the recent fauna and flora are distributed. There is, to 

 be sure, more or less intermingling of species. The myriapods, 

 as far as they have been found, are localized. Mr. Carr found 

 three within a space of a few feet. But again these are 

 found widely scattered. The exposures at the " upper beds " 

 are about a quarter of a mile long. They disappear under a 

 heavy ledge of sandstone. 



