S E D I M E N T A N A LY S I S U S E D T O
P R O D U C E A PA L E O C L I M AT I C
RECORD FOR THE SAN JUAN,
COLORADO REGION
Jacob E. Buettner
Dr. Bryan Shuman &
Jeremiah Marsicek
Geology and Geophysics
PROPOSED RESEARCH PROJECT
Introduction
Methods for Analysis
Importance
The Rocky Mountain region has a midlatitude steppe climate and has wet and
dry season variability. The region is
reliant on snow pack from the high
mountains to supply water to rivers and
watersheds. To understand current and
future climate, watershed, and snow
pack variations we look to the past.
Small lakes with no inlet or outlet
source, other than snowpack melt,
provide a past climatic or precipitation
gage record for a given region.
Methods will include grain size (% sand content; steps below) and sediment density
analyses of lake bed sediments for use in producing a moisture availability record.
Dense, sandy intervals represent periods of low water, and less dense, silty
sediments (mainly organic) will represent high stands. 1 cm3 subsamples of
sediment will be removed at contiguous intervals throughout the core for analysis.
The importance of this study is to
analyze and understand the past water
availability in the Rocky Mountain
region to help inform future trends.
Water availability is a critical issue in
the Rocky Mountain region and for the
rivers that are fed from the Rocky
Mountain watersheds. Understanding
past trends in water availability and
possibly what drove them can help
forecast potential trends of future water
availability. Ultimately, this data can
assist in implementing proper water
management systems for the future.
Statement of the
Problem
The purpose of this study is to establish
a moisture-level record for the San
Juan, CO region using grain size and
sediment density analyses of lake bed
sediments from Little Molas Lake, CO.
This lake was selected because it has
no inlet or outlet stream, and so acts as
a precipitation gage for the past
~11,000 years (lake’s history).
Step 1: The 1 cm3 will be weighed, burned at 110 °C and 550 °C, to evaporate
water and burn off organic matter, respectively, and then reweighed to obtain the
percent water and percent organic matter contained in the sediment sample.
Step 2: The 1 cm3 cooked sample will be screened using a 63 micron sieve. If the
sediment goes through the sieve it, then by definition it is not sand. The sediment
contained in the sieve, sand, will then be weighed and burned at 550 °C to remove
any large organic material, and weighed again.
Step 3: Intervals that show evident change in sediment type (i.e. silt to sand) will
then have one milligram of charcoal removed to date the time of the change.
North
Cross Section of Little Molas Lake
Scenic view of Little Molas Lake
Arial view of Little Molas Lake
Objective
Acknowledgements
The objective of this project is to
identify water availability during the
last ~11,000 years in the San Juan,
Colorado region.
From Google Maps: Topographic View
South
Dr. Bryan Shuman,
Jeremiah Marsicek,
Zackie Salmon &
Susan Stoddard
Core sample from Hidden Lake Colorado; It shows a portion of the sediment record