Mud. 



424 



caster, York and Adams counties. Figure taken from Zittel's 

 Handbuch, Vol. 3, p. 776, fig. 980, enlarged three-fold, — Trias 

 formation. 



Mud flow, fossilized.^ Owen, Geol. of Wisconsin, Iowa and 

 Minn. 1852, plate 1, fig. 1, a medal ruled relief picture of the 

 surface of a slab of argillacious grit ; relief from quarter to 

 half an inch ; not like any ripple markings on a shore ; rock 

 resembles volcanic grit ; suggests volcanic mud descending a 

 hillside from a fumarole. Red sandstone of the shore of Lake 

 Superior. Cambrian ? — The Portage flags in New York and 

 in Pennsylvania show an abundance of mud flow surfaces which 

 cannot be ascribed to any volcanic action, and therefore it 

 seems needless to seek such an origin for those of Cambi'ian 

 age, Q4, p. 119. — In Bedford Co., Pa., mud flow casts are num- 

 erous on nonfossiliferous olive Chemuny flags,, in King town- 

 ship, Imlers cross roads. Stevenson, T2, p. 133. — In Hunt- 

 ingdon Co. they appear on the flags {Portage?) exposed be- 

 low Huntingdon, Oeds No. 63 of the Pa. R. R. cut section, with 

 fucoides graphica, I. C. White, T3, p. 265.— VIII f, g, 



Murchisonia abbreviata, Hall. Pal. New York, Vol. 1, 

 He. y^iL 1847. Ghazy group. — Emmons, Am. Geol. Vol. 

 1, part 1, 1855, p. 162, plate 4, fig. 11, llc\ rare 

 in the Birdh eye limestone of N. Y. Emmons. — 

 S. A. Miller's Oat says that Hall's name was 

 PI 4 preoccupied by DeKoninck in 1841. 

 Murchisonia angustata, Hall, Pal. N. Y. Vol. 1, 1847. 

 Bird'^s eye limestone lie. Recognized byC. E, Hall in the col- 

 lections of 1875 in the Kishicoquilis Valley, Mifflin Co., Pa. 

 BlacJcriver limestone lie, — See Appendix. 

 Murchisonia anna, Billings. Can. Nat. and Geol. Vol. 4, 



^^ 1853. Geol. of Canada, 1863, 

 page 119, fig. 32 a; figs. J, c, 

 d^ 6, /*, are five small speci- 

 mens supposed to be of the 

 same species. Calciferous 

 ^^^^ sandstone,^ Ila, 



£m.A.G: 



l/d 



<0 -^^ 



. Cdr/. 



* For figures see page 435. — See also Hall's excellent wood 

 cut in Geol. N. Y. 1843, page 233, fig. 101, which will be repro- 

 duced in the Appendix. 



