SCUDDER.] TERTIARY LAKE BASIN OF FLORISSANT. 275 
southern half, where it cannot fail to strike the observant eve upon the 
spot, the southernmost margin, close to the summit of the divide, being 
nearly two hundred meters higher than the margin next the school-house 
hill. 
Our examination of the deposits of this lacustrine basin was principally 
made in a small hill, from which perhaps the largest number of fossils 
have been taken, lying just south of the house of Mr. Adam Hill, and 
upon his ranch. Like the other ancient islets of this upland lake, it 
now forms a mesa or flat-topped hill about ten or a dozen meters high, 
perhaps a hundred meters long and twenty-five broad. Around its 
eastern base are the famous petrified trees, huge, upright trunks, stand- 
ing as they grew, which are reported to have been five or six meters 
high at the advent of the present residents of the region. Piecemeal 
they have been destroyed by vandal tourists, until now not one of them 
rises more than a meter above the surface of the ground, and many of 
them are entirely leveled; but their huge size is attested by the relies, 
the largest of which can be seen to have been three or four meters in 
diameter. These gigantic trees appear to be sequoias, as far as can be 
told from thin sections of the wood submitted to Dr. George L. Goodale. 
As is well known, remains of more than one species of sequoia have been 
found in the shales at their base. 
At the opposite sloping end of this mesa a trench was dug from top 
to bottom to determine the character of the different layers, and the 
section exposed was carefully measured and studied. In the work of 
digging this trench we received the very ready and welcome assistance 
of our companion, Mr. Bowditch, and of Mr. Hill, the owner of the 
grounds. 
From what information we could gain about the wells in this neigh- 
borhood it would appear that the present bed of the ancient Florissant 
lake is entirely similar in composition for at least ten meters below the 
surface, consisting of heavily bedded non-fossiliferous shales, having a 
conchoidal fracture. Mr. Peale does not say whether the well seen by 
Mr. Taggart passed below the trachyte, which he says it first entered. 
Above these basal deposits, on the slope of the hill, we found,the fol- 
lowing series, from above downward, commencing with the evenly bed- 
ded strata: 
Section in southern lake. 
[By S. H. ScuppER and A. LakEs. ] 
Centimeters. 
1, Finely laminated, evenly bedded, light-gray shale; plants and insects scarce 
ANGE POOL WA DECSET VEC ey ec jaapiaretseiavyal ) Mu vera ep lae. ive sube maar Apsara ie 3.2 
2. Light-brown, soft and pliable, fine-grained sandstone; unfossiliferous.... 5 
3. Coarser, ferruginous sandstone; unfossiliferous...--...----..--.2..----- 3.8 
4, Resemblng No.1; leaves and insect remains ...4 522. 2 ciso. ela bencce 21 
5. Hard, compact, grayish-black shale, breaking with a conchoidal fracture, 
seamed in the middle with a narrow strip of drab shale; fragments of 
TUE USY Oe sg ie er ce Se eae ae Ieee eine MIke CES oa ae amr a oc Re Se ges 28 
Se Resrieinons sales mntossiiferodg si, oo sce psiotas sous hacia ve Sbiocjee oes 1.5 
7. Resembling No. 5, but having no conchoidal fracture; stems of plants, in- 
sects, and asmall bivalve mollusks... cela Seek eee Le ee 9 
8. Very fine gray ochreous shale; non-fossiliferous...-......--....--.------ 0.5 
9. Drab shales, interlaminated with finely-divided paper shales of light- 
gray color; stems of plants, reeds, and insects........-...------------ 46 
10. Crumbling ochreous shale; leaves abundant, insects rare.....-..---- ----. Po 
OLA SUAS ss TO LOSS Street ase ntoneetee waite oeise ee anoce Sak Loe ccccNeoe ee Geb 
12. Coarse, ferruginous sandstone; no fossils.......------ .----0 enone -- eee 3,8 
13. Very hard drab shales, having a conchoidal fracture and filled with nod- 
Biles ie CREOSEL ROT OU tas eira ep ven oh Ie aleinn cis inc debs san & areimelae oessie «dee 
14, Finely laminated yellowish or drab shales; leaves and fragments of plants, 
SADT RO WELD CLO. etmamiia nen tna vin «ole alsiciinin pie/civia slaaieis mola alo eeiete aie 30 
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