DENVER OF SOUTH TABLE MOUNTAIN. 165 



Basalt, at top. Feet. 



0. Dark-brown clays and fine gravel in alternating layers. 11 

 9. Coarse gravel and pebble-bearing bed 5 



5. Gravel layer at bottom, passing gradually into a dark, 



reddish-brown clay at top 18 



7. Conglomerate of small, dark andesite pebbles 2 



6. Fine-grained, light-colored sand rock or tuff 5 



5. Finegrained rock, like G at base, passing into clay at 



top 20 



4. Dark clays, often mottled, containing small pebbles of 



light-colored andesite and tuff 34 



3. A series of alternating light-colored clays and seniicon- 



glomeritic or tuffaceous layers ... 52 



2. Friable sand rock and sandy clays 18 



1. Sand rock, more compact than 2 •> 



Total 171 



In division '2 of the section there is a general distinction to be made 

 between the lower 8 feet, which are dark-colored through the abundant 

 admixture of vegetable matter, and the upper Id feet, which are firmer and 

 contain less carbonaceous substance, though stems and imperfect leaves 

 of plants are common. Some of the lower layers are chiefly made up of 

 plant remains. 



Under division ,'i are included strata of peculiar constitution which are 

 well developed in some places not far from this exposure, but do not appeal' 

 at many other points where it seems likely they would be distinguishable 

 if of the character here presented. In the section the division begins 

 with some almost conglomeritic pebbles of a light-yellow or straw-colored 

 andesite, and others of reddish or brownish colors. The latter are merely 

 decomposed rocks similar in kind to the darker ones of other horizons, while 

 the light andesite is of a variety found only in 3, 5, and G of the section. 

 Passing upward in the series there is an alternation of clay, or what may 

 he more expressively termed mud layers, with gravel or sand rock. The 

 strata of this complex vary in thickness from a few inches to G feet or 

 more and are laterally variable in this respect. The coarser-grained beds 

 show cross-bedding. The mud layers are easily removed by water on 

 any exposed surface, and so leave projecting shelves of the intermediate 



