814 



Popular Science Monthly 



making cement. The re- 

 maining rock is also lime- 

 stone, but as it is not of the 

 proper consistency for mak- 

 ing the best cement, it was 

 left intact. 



When rock is bowed or 

 arched up in this manner, 

 the result is termed an 

 anticline. This anticline is 

 exposed at several points 

 along the Chesapeake and 

 Ohio Canal, Maryland. 



When the Appalachian Mountains were lifted above 

 sea-level, millions of years ago, these strata of limestone 

 were arched up like a bubble in pie-crust. The core 

 of the rock has been partly mined out to make cement 



Rock Folded Like 

 Cardboard 



THE rocks in this photo- 

 graph which are seen 

 to be bent over in the shape 

 of a loop were at one time — 

 some millions of years ago — 

 the flat bed of the ocean. 

 When the Appalachian 

 Mountains were uplifted 

 above the sea they were 

 raised with the rest of the 

 land, and as the uplift was 

 irregular these strata of lime- 

 stone rocks were bowed up 

 like a bubble of a pie-crust, 

 which is lifted by the gas 

 generated in the cooking of 

 the pie. The core of this 

 rock has been mined out for 



The House That Tin 

 Cans Built 



YOU have heard of the 

 house that Jack built 

 and you may have read 

 about the house that junk 

 built, but did you ever hear 

 about the house that tin 

 cans built? Huts built from 

 tin cans — five gallon gasoline 

 cans — are not at all un- 

 common in that section of 

 America between the Rio 

 Grande and the Tierra Del 

 Fuego, as in the locality the 

 five gallon can is a generally 

 accepted standard of liquid 

 measurement. While not en- 

 tirely suited for a dwelling in 

 Mexico, because it is not bul- 

 let-proof, this tin can house 

 is very comfortable. 



There is no such word as "can*t" for the man who 



built this house; but he uses can frequently, his house 



being made of five-gallon gasoline cans 



