MARYLAND 409 



617. "The Shenandoah near Harpers Ferry (No. 237). 



618. The Great falls of the Potomac (No. 238). 



Massachusetts 



Photographed by George P. Merrill, United States National Museum 

 6| by 8-| inches 



619. Marine erosion of till, Long Island head, Boston harbor (No. — ). 



620. Ship rock, Massachusetts. A glacial-drift boulder at Peabody. This boulder 



is 51 feet long, 27 feet wide, and 31 feet high. View from the north. The 

 source is probably local (No. — ). 



621. Roche moutonnee, Marblehead, Massachusetts (No. — ). 



622. Marine erosion of till, Boston harbor. Cliff on eastern edge of Great Brewster 



islands (a drumlin) (No. — ). 



Photographed by S. R. Stoddard, Glens Falls, New York 

 5 by 8 inches. Price, 50 cents each 



623. Monomoy point; looking northward from Monomoy light-house, Cape Cod. 



Massachusetts (No. 1207). 



624. The "powder-hole," Monomoy light-house, from the light-house (No. 1206). 



Mexico 



Photographed by O. P. Farrington, Field Columbian Museum, Chicago, Illinois 



5 by 7 inches 



625. Porfirio Diaz glacier, Ixtaccihuatl, Mexico, from the old terminal moraine 



(No. 12). 



626. Weathering of quartz vein near El Bote mine, Zacatecas, Mexico. The 



surrounding rock is chlorite schist (No. 13). 



627. Section of lava flow, El Pedregal of Tialpam, near San Angel, valley of 



Mexico. The vesiculation of the lava by escaping vapors is shown and 

 the increase through relief of pressure in the size of the vesicles toward 

 the upper surface (No. 14). 



Michigan 



Photographed by I. C. Russell, 1881 



8 by 10 inches. Negatives in United States Geological Survey 



628. Sea-cliff in limestone, Mackinaw island, Michigan (No. 174). 



629. Sea-cliff in sandstone, small island near Marquette, Michigan (No. 167). 

 Nos. 630, 631, 635, 638, 640, 641, 643 are published by G. K. Gilbert in Fifth 



Annual Report U. S. Geological Survey. 



630. Sea-cliff in hard sandstone, with beacli beyond, Au Train island, lake Su- 



perior (No. 172). 



