92 Expedition to the 



appearances are so remarkable, that it is not surprising 

 these rocks should have been considered of volcanic origin, 

 and it is this supposition, unquestionably, from which has 

 originated the statement contained in the late map of the 

 United States, by Melish, that the district about the sources 

 of Red river, is occupied by volcanic rocks; this information 

 having probably been derived from the accounts of hunters. 



The vallies which penetrate into the sandstone, supporting 

 the trap rocks, have usually a sandy soil, while that of the 

 more elevated portions, though inconsiderable in quantity, is 

 not sandy nor intermixed with pebbles or gravel. Among the 

 few scattered end scrubby trees, met with in this district, are 

 oaks, willows, and the cotton-wood; also a most interesting 

 shrub or small tree, rising sometimes to the height of twelve 

 or fourteen feet. It has dioiceous flowers, and produces a le- 

 guminous fruit, making in several particulars a near approach 

 to Gleditschia, from which, however, it is sufficiently dis- 

 tinguished by the form of the legume, which is long and 

 nearly cylindiric, and by the seeds, which are enclosed in 

 separate cells, immersed in a saccharine pulp, but easily de- 

 tached from the valves of the legume. In these particulars 

 it discovers an affinity to the tamarind of the West Indies. 

 The legume or pod, which is from six to ten inches long, 

 and near half an inch in diameter, contains a considerable 

 quantity of a sugar-like pulp, very grateful to the taste when 

 ripe. The leaves are pinnated, and the trunk beset with 

 spines, somewhat like the honey locust, but the spines are 

 simple. Our Spanish interpreter, informed us that it is found 

 about Monterey, and in other parts of the internal provinces, 

 where it must have been noticed by Humboldt; but we have 

 not been able to have access to his account of it. 



In the afternoon, we travelled thirteen miles, descending 

 along the valley in a southeast direction. We extended our 

 ride farther than we had wished; finding no suitable place 



