:!.VJ THE GEOLOGY OF MINNESOTA. 



[Cretaceous strata 



much like ocher, varying in color, from u dark burnt-umber color to a 

 lighter shade, even to buff', and appearing when of a light color much like 

 the mass of number 3. They can bo scratched easily with a knife, and 

 however black they may be, they give a red Im-matitic streak. When they 

 are faded the streak also fades into a brown or yellowish-brown like limo- 

 nite. Intermingled very irregularly with number '2. and sometimes also 

 with number 8, are masses of greenish clay which has in ev-ery other re- 

 spect the same outward characters as number 2. There are here also large, 

 crystalline, detached masses of apparently a siliceous limestone which is 

 very hard and close-grained. In some cases, however, this varies to a 

 porous and nearly white limestone that appears to be very pure.* 



In the digging of Mr. L. G. Basford's well, at Austin, the rock quarried at Austin was struck 

 at twenty-four feet and was penetrated eight feet. Overlying this was a deposit of blue clay. 

 This deposit was also found in the crevices of the rock. The clay contained angiospermous leaves. 

 Two distinct varieties of leaf were discovered, one resembling /Wo/<///w /'//,/,<! /. lir.. and the 

 other a species of Sequoia. The specimen of the latter consists of a branch, apparently of a small 

 herb. It shows an inch and three-fourths of the main stalk. In that distance it gives off four 

 branches, each of which seems to be as large as the main stalk, three on the left and one on the right. 

 The whole specimen is thickly furnished with decurrent, parallel-veined leaves, which have a dis- 

 tinct midrib. The leaves are simple, entire, oblanceolate linear, and taper-pointed at their junction 

 with the stalk. Their length is a quarter of an inch, varying a little above and below that size, 

 and their width is one-twentieth of an inch. The diameter of the stalk, and that of the branches, 

 is about one-half the width of the leaves. The latter diverge from the branches at an angle of 40 

 to 45 . A photographic copy of this fossil was submitted in 1874 to Dr. J. S. Newberry, who pro- 

 nounced it probably a species of Sei/uoia; and Dr. Leo Lesquereux. on examination of the original 

 specimen, regards it as a new species.f 



Near the mill of Jonathan Gregson, about two miles below Austin, the 

 palaeozoic rock is cut by old channels and other cavities, and these are filled 

 with blue clay of the same character as that containing the angiospermous 

 leaves at Austin. It shows here no fossils nor shells of any kind. It is 

 exceedingly tine and plastic. It is said to run down at least thirty feet, 

 where the stone itself would naturally lie if the strata were continuous. It 

 seems to occupy a trough-like excavation in the rock about a rod wide run- 

 ning east and west, and has been traced by means of an iron rod several 

 yards back from the river bank. This clay below twenty feet is said to be- 

 come white. 



Besides this clay there is a irhitr *<iinl. supposed to underlie the clay, 



*In connection with this description of limestone masses, it i interesting to note the occurrence at St Charles in 

 Wfnona county, of hard siliceous limestr.me masses on the surface of the ground, appearing very much like those 

 embraced in this clay, and also in Fillmore county southeast of Spring Valley 



i the first and third annual reports tliese fossil i,. :lvi ..s were wrongly referred to the Austin rock, and on the 



reiigth of that information the Austin rock was ri- K .i,d, ,1 ( .vtac.ous. A late re-examination of the loca ity, and an 



interview with Mr. Charles Bromwick, have established the fact that they are only found in the clay deposit overlying 



