138 GUIDEBOOK OF THE WESTEEN UNITED STATES. 



of tlie craters and flatten toward the base, where they become nearly 

 horizontal. Withm the crater run the beds slope toward the center. 

 Sand and gravel contamed in the strata of which the craters are built 

 indicate that these volcanoes were upheaved somewhat explosively 



throug 



There is nothing to show that 



either cone poured out a lava stream. Material brought into the 

 craters by rain wash and wind has given fairly level floors to the 

 broad bowl-shaped depressions. The two cones are supposed to be 

 of about the same age and are moderately recent. The name was 

 derived from their proximity to Market Lake, a former shallow body 

 of water so called because ducks congregated on it in such numbers 



ma 



that hunters went there regularly for a supply of meat. 



A black volcanic tuff, an open-structured rock 

 cemented fragments and dust produced by volcanic explosions, is 

 used for building in the vicinity of Rigby and Rexburg. This rock is 



Market 



Craters. Houses 

 abmidantly in th( 



After 



o 



g^«::o ui^^^^iA^iJ. tx ^ 



cottonwoods along the channels of the river. This is the only natural 

 grov(f on the railroad between Ogden and the Targhee National 



Forestj north of Ashton, 



A mile or two east of Thornton a bluff rises abruptly 100 feet or 



more 



'f this 



forms 



Thornton. basalt that makes the floor of the Snake River plain. 



Elevation 4,s59 feet, ^hc relative agcs of the two rocks are indicated by 

 g en mi e^. ^^^ ^^^^ that the rhj'olite is deeply weathered and in 

 places its beds are disturbed from their original nearly horizontal 

 attitude, while the basalt is unweathered and its horizontal beds 

 abut against or overlap the older rhyohte. 



Several miles to the west there is a low-lying light-colored band of 

 sand dunes with a group of hills at its north end. 



From Winder, a siding and beet-loading platform, a clear view may 

 be had of the Market Lake Craters. Concrete tile for culverts is made 



here from sand and gravel dug beside the track. 

 Winder. j^g^j. j^gxburg the train crosses a large irrigating 



Elevation 4,856 feet. j-i t ±i i. e i-i- ■, « ^ ?>. 



ogdea 207 miles. ditcJi, the Water for which is taken from Teton River. 



Ricks Academy, a Mormon school, stands near the 

 edge of the town. The 



this resrion attest the fi 



numerous 



overflow population from Utah. In the late seventies and early 

 eighties the fertile spots of northeastern Utah were aheady occupied 

 and the stream of emigrants moved northward into Idaho 



