Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 5-1928 The Devonian of the Bear River Range, Utah I. Lavell Cooley Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Geology Commons Recommended Citation Cooley, I. Lavell, "The Devonian of the Bear River Range, Utah" (1928). All Graduate Theses and Dissertations. 5613. https://digitalcommons.usu.edu/etd/5613 This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. i I -----------~-·-·--- AGRICULTURAL COLLEGE OF UTAH I .•nn. 8 •· ~· THE DEVONIAN OF THE BEAR RIVER RA NGE, UTAH I A DISSERTA TION SUBMITTED 'TO THE GRADUATE FACULTY I N GA NDIDAGY FOR THE DEGREE OF MASTER OF SCIENCE. I f@©'"li 'fi r'' ~· DEPARTUEN T OF GEOLOGY ,..,.,.,...-...... ~ · .il!" .. ·.::, ~ ' BY I. LAVELL COOLEY LOGAN,UTAH I JULY, 192t5. I I I ,, I s : 1 __ ie. ~· '! ~ . 1 ~_1 I C 0 N 'I' E N T S I I INTRODUCTION 'I PHYSIOGRAPHY STRUCTURE I STRATIGRAPHY Devonian System I 1. Location 1·,,, 2. Distribution ~-) .L B(! ~} __Thickness and Lithology I 4. Conditions of Deposition 5. Fossils I 6. Age and Correlation I With columnar section, graphic sections and photographs I I I I ---.-..-. ---··---------------' - ---- -.------- ---·- ---- ---- ----- ----- ------~-----------------' I tv . I ~ · I -2- INTRODUCTION I The geelogical column in northern Utah has haa very little detailed study~ Those Who have made re­ I ports on this section have done so only in a very general way, making no detailed sectio-ns of any part I of the column, excepting that of the Cambrian made I by Walcott. l Other work has been done by. Mansfield2 in southeastern Idaho and a general section of the I. Devonian made in Green Canyon, Bear River Range, Utah by Kinctl:le. 3 I Due to the lack of any detailed work of this nature being done in the Bear River Range, suggested the matter of making a section and describing the I .Devonian System of thi-s Fan.ge, because, probably less is known of this system than of any other one. I Stratigraphic relations were studied in several II seetions where outcrops were good. Conditions for the study of these outcrops are very favorable, because, I within a very short distance of 6 or 7 miles there are 6 canyons cutting the range at approximately right an- I gles to the general trend of the structure, giving satisfactory sections of the greater part of the Paleo- I zo·ic Era. Blacksmith Fork Canyon gives the best I 1 S'mi thsonian Miscellaneous P-apers # :53. --·------ --------2--F r ofess-:rona17aper- r r5z:---------------- - - ---------------------- _.) 3 ~ul. Am. Paleontology, vol. 4, No. 20, 190t), pp. 5-24; 1 ta) pp. 10-13; (b) pp. 15-16. I I - 3- I/_r ' I I section of the Devonian System in the area studied. I Because of easy aceess and good exposures, this aan- yon-was chosen for a graphic section. Another sec- I tion was made in Logan Canyon as a matter of compar- ison. .........-.•-, I A - A is a general graphic section of the front ridge of the Bear River Range, showing the structure I on the north side of Logan Canyon, situated almost (Plate II) I directly east of the city of Logan, Utah./ B - B is a general graphic section of the front ridge showing I the structure on the north side of Blacksmith Fork Canyon. These graphic sections constitute the gen- ~ -~) · - ----~---/ eral lithological character of that portion of the I Paleozoic Era which makes up this part of the Bear River Range. The eastern portion of the range is a I faulted anticline and is capped, uncomformably, by I Tertiary deposits. I I ti l I ' .. I I - "t- I I PHYSIOGRAPHY I The Bear River Range is a relatively rugged mass with the exception of the eastern portion which consti- I tutes a more or less plateau-like topography. The range is continuous with the Wasatch Range proper, and I is really a branch of the northern extremity of that I range. Geologically and ph·y Biographically that portion of the Wasatch Range from a position in the vicinity I of Huntsville, Utah, about latitude 4f 15' ~ and runs in an almost true north-south direction along the east I side of ·Cache Valley and terminates at Sheep Rock just south of the sharp bend of Bear River near Alexander, Idaho, is termed the Bear River Range (Plate I and I-A). I The other main branch of the Wasatch which forks off from about the same latitude and runs in the same I direction, but borders the west side of Cache Valley, I and terminates in a low, rolling topography at the point where Bear River passes through a gorge from I Cache Valley on it's way to Great Salt Lake, is the . Wellsville Range (Plate III.). This range has a very .. I sharp crest line which is almost impassable in places. The east slope of the range is almost a dip slope. / / ' I The Bear River Range as described above, has a I length of about 95 miles and varies in wid.th from 2 to ~~ )- ·· ---- ___ 22 mifes_;___ tb.e - maxT mum -wrcfEn- bei ng -aT ong--fJie--ri n e o e-=- ----- --'---- 1 -5- I ----) I· /'' I tween Tps 15 and 16 So. in southern Idaho. North of North of this line it grows narrower and terminates I at Sheep Rock. The range consists of two roughly I parallel ridges; the more rugged on the west called the Bear River front ridge, the lower plateau-like I mass to the east, the Wasatch Range. These ridges merge to the south in the Wasatch Range proper. I The Bear River front ridge is formed from a broad, I shallow, syncline with the highest portion along the axis of the syncline. The lower plateau-like Wasatch I Range to the east is a badly faulted anticline which is in part unconformably overlain with Tertiary con- I ) glomerate, sandstone and limestone. I The front ridge takes on a rugged topography with serrate crest line, steep ·slopes, gorge-like can- I yons, glaci~ted valley heads and pre£ents a steep and rugged front toward Cache Valley. I The highest peaks in the range are from north to I south; Paris Peak 9,572 feet, Sherman Peak 9,669 feet, in southern Idaho; Naomi Peak 9,980 feet, Logan Peak I 9,713 feet, in northern Utah. I I 1-----------------) -- ---~--- - -- -- --------------- ---- - I I - 6- I ( ·-'\ ) I STRUCTURE Over the immediate vicinity of the Bear River I Range with which thi~ paper is concerned, the rock I outcrops of the P aleozoic are very abundant and well defined. This condition is due partly to the Bear I River Range gravity fault and subsequent erosion, which has exposed the strata ranging from Cambriati to Penn- I sylvanian. I One very interesting feature which comes to the attention of the observer and which arouses his curio- I sity is the structure of the strata on the west limb of the broad shallow syncline, which makes up the front t~- - / ) ridge of the range. The strata have an average dip of I 18-20 degrees. At the mouth of Logan and Dry G.anyons, the gentle easterly dip of the strata is abruptly chang­ I ed, being sharply bent to a vertical and partially over- turned position, making the Ordovician and Silurian beds I occur in a reverse order (Plate IV a and b). Not only I is this spectacle of natural architecture of great inter- est, but associated with it is a zone in which the rocks I have lost their original form and are very badly brec:- .::, ciated and fractured. This impressive feature, together I with the finer observations of local folding and. buckl- ing of the thin-bedded incompetent formations bring a- I • I- - )--- -------- -- ----- - -- --- ------------ ----- - --- --- - - I -7- I I -·I' \ : I bout a conclusion that this area was subject to in- I tense compression, which obviously came before the brea.ki ng of the Bear River Range gravity fau 1 t. This I zone of fracture and folding extends up Logan c·anyon approximately 1000 feet. I Another impressive feature.of the range is the I clean-cut gorges which the major streams have made througjh the front ridge, exposing on both sides bare rock ledges I of which form a great part of the Paleozoic -Era. These continuous outcrops, layer upon layer, gently folded to I form the broad end shallow syncline, interrupted here and there where local faulting has occured, reveals to one l _) the great phenomena of mountain bu ilding and architecture. I Most of the streims in this portion of the Bear River Range have their source in the lower, eastern section and I flow west through the hi gher front ridge at a lmost right I angles to it's trend. A considerable amount of up-lift- ing of the range must have occured after the strea~s had I their courses pretty well defined. This condition is explained by the entrenched meanders occuring in the left I fork of Logan Canyon, in the vicinity of Temple Fork and I the superimposed appearance of the front ridge. I -- -·------ -------- ------- ----- ------ -- ---- -- - - - ---·- ---- ---------- ----- -----------:+,1 ~T ~ --~---- ------------ I '• I -tJ- I t \) I STRATIGRAPHY I The systems represented in the Bear River Range show little differentiation lithologically; the roak I being predominantly limestone and dolomite, with small amounts of sandstone, shales and quartzite.