Geology of the Pacoima Area, Los Angeles County, California

The Pacoima area is located on an isolated hill in the northeast section of the San Fernando, the northeast portion of the Pacoima Quadrangle, Los Angeles County, California. Within it are exposed more than 2300 feet of Tertiary rocks, which comprise three units of Middle Miocene (?) age, and approximately 950 feet of Jurassic (?) granite basement. The formations are characterized by their mode of occurrence, marine and terrestial origin, diverse lithology, and structural features.

The basement complex is composed of intrusive granite, small masses of granodiorite and a granodiorite gneiss with the development of schistosity in sections. During the long period of erosion of the metamorphics, the granitic rocks were exposed and may have provided clastic constituents for the overlying formations.

As a result of rapid sedimentation in a transitional environment, the Middle Miocene Twin Peaks formation was laid down unconformably on the granite. This formation is essentially a large thinning bed of gray to buff pebble and cobble conglomerate grading to coarse yellow sandstone. The contact of conglomerate and granite is characterized by its faulted and depositional nature.

Beds of extrusive andesite, basalt porphyry, compact vesicular amygdaloidal basalts, andesite breccia, interbedded feldspathic sands and clays of terrestial origin, and mudflow breccia comprise the Pacoima formation which overlies the Twin Peaks formation unconformably. A transgressing shallow sea accompanied settling of the region and initiated deposition of fine clastic sediments.

The marine Topanga (?) formation is composed of brown to gray coarse sandstone grading into interbedded buff sandstones and gray shales. Intrusions of rhyolitedacite and ash beds mark continued but sporatic volcanism during this period.

The area mapped represents an arch in the Tertiary sediments. Forces that produced the uplift of the granite structural high created stresses that were relieved by jointing and faulting. Vertical and horizontal movement along these faults has displaced beds, offset contacts and complicated their structure. Uplift and erosion have exposed the present sequence of beds which dip gently to the northeast. The isolated hill is believed to be in an early stage of maturity.

Geology alive. GeoBizirik.org

Geology is the science that studies the Earth, its composition, structure and origin in addition to past and present phenomena that leave their mark on rocks. So why does society need geologists? Some of the main reasons are listed below: - Geologists compile and interpret information about the earth’s surface and subsoil, which allows us to establish the planet’s past history, any foreseeable changes and its relationship with the rest of the solar system. - Society needs natural resources (metals, non-metals, water and fossil fuels) to survive. The work of geologists is therefore a key part of finding new deposits and establishing a guide for exploring and managing resources in an environmentally-friendly way. - The creation of geological maps allows us to identify potential risk areas and survey different land uses; in other words, they make an essential contribution to land planning and proposing sustainable development strategies in a region. - Learning about Geology and the proper use of geological information contributes to saving lives and reducing financial loss caused by natural catastrophes such as earthquakes, tsunamis, volcanic eruptions, flooding and landslides, while also helping to develop construction projects, public works, etc. Through the proposed activities we aim to explain some of the basic elements of the different specialities within the field of Geological Sciences. In order to do this, four sessions have been organised that will allow for a quick insight into the fields of Palaeontology, Mineralogy, Petrology and Tectonics.

Geology alive. GeoBizirik.org

Geology is the science that studies the Earth, its composition, structure and origin in addition to past and present phenomena that leave their mark on rocks. So why does society need geologists? Some of the main reasons are listed below: - Geologists compile and interpret information about the earth’s surface and subsoil, which allows us to establish the planet’s past history, any foreseeable changes and its relationship with the rest of the solar system. - Society needs natural resources (metals, non-metals, water and fossil fuels) to survive. The work of geologists is therefore a key part of finding new deposits and establishing a guide for exploring and managing resources in an environmentally-friendly way. - The creation of geological maps allows us to identify potential risk areas and survey different land uses; in other words, they make an essential contribution to land planning and proposing sustainable development strategies in a region. - Learning about Geology and the proper use of geological information contributes to saving lives and reducing financial loss caused by natural catastrophes such as earthquakes, tsunamis, volcanic eruptions, flooding and landslides, while also helping to develop construction projects, public works, etc. Through the proposed activities we aim to explain some of the basic elements of the different specialities within the field of Geological Sciences. In order to do this, four sessions have been organised that will allow for a quick insight into the fields of Palaeontology, Mineralogy, Petrology and Tectonics.

The River Lune strategic stock assessment survey 1991 with particular reference to salmonids

In the past stock assessment surveys were generally reactive in response to a particular problem e.g. a pollution incident and as such were limited in the information they provided. A programme of strategic stock assessment would be more beneficial, providing up to date information on the status and composition of the stock. On a national level this could reveal trends in population dynamics and enable comparisons to be made between key rivers and between regions. The Stock Assessment Task Group (1991) has recommended annual strategic surveys for juvenile salmonids and triennial strategic surveys for coarse fish and non- migratory salmonids. The aim of this pilot study was to gain information on species distribution and their relative abundance within the River Lune catchment, and to compare the findings with the surveys carried out between 1981-1985. This would provide valuable information on the current status of the stock and provide an indication of the resources required to conduct such strategic surveys on other river catchments in the North West Region of the National Rivers Authority.

Preliminary report on the coarse fishery status in the River Lune with particular reference to the Lansil Fishery

This study takes a preliminary step towards investigating the reports of poor rod catches of coarse fish in the River Lune. These poor catches and concern over the possible loss of coarse fish from the Lower Lune is investigated, using creel census data from 1991. Historical data is used where available for comparative studies. The conclusion that this report comes to is that there is a problem with the recruitment of coarse fish within the population. Dace, roach and bream all show good growth rates but only poor if any recruitment. Historical investigations suggest that roach and bream may never have successfully recruited without artificial induced conditions. The situation with dace is of more concern as populations in other rivers in Northern England are also in decline, whilst historically they were naturally recruiting.

The juvenile salmonid populations of the River Lune catchment, 1981 to 1985

The aim of this study was to assess the status of the juvenile salmonid populations of the River Lune and its tributaries. There was special emphasis on juvenile salmon stocks in view of the implementation of a net limitation order in 1980. The number of licensed instruments were reduced as follows: (1) Drift, hang or whammel nets - from 12 to 10 (2) Draft or seine nets - from 3 to 1 (3) Heave or haaf nets - from 4 6 to 2 6 For the purpose of this report, the River Lune system has been divided into 13 subcatchments and these are examined with a view to detecting any trends in the data such as subcatchment productivity, partitioning between salmon and trout nursery streams, and whether the restrictions on salmon fishing had any discernible effects on juvenile salmon productivity. The effect of flow and instream obstructions on salmonid densities are also investigated as these have been shown to be important factors affecting abundance. Throughout the study period a programme of enhancement stocking took place primarily with salmon ova and fry. The possible impact of this on the results of the surveys has been assessed. The distribution and abundance of juvenile salmon was found to be relatively consistent in each of the 13 subcatchments studied over the 1981-1985 period.

A summary report on juvenile salmonid populations of the River Lune catchment, 1981 to 1991

This report summarises the fisheries electrofishing survey work undertaken on the River Lune, England, in the period 1981-85 and 1991. As part of a long term monitoring programme by the National Rivers Authority, juvenile surveys, with the emphasis on salmonids, have been carried out on the River Lune on a number of occasions since 1981. The latest survey in 1991 now gives the opportunity to assess what, if any, changes have occurred in the juvenile populations across the last 11 years and how future fisheries management may impact on the River Lune as a fishery. The areas of trout and salmon, fry and parr production will be considered in detail, as will adult trout populations. Water quality issues will be mentioned briefly as will habitat issues, where they are deemed to be important in affecting fish densities.

Salmon action plan consultation. River Lune - draft

In February 1996 "A Strategy for the Management of Salmon in England and Wales" was launched by the then National Rivers Authority. The strategy concentrates on four main objectives for the management of salmon fisheries in England and Wales. These are primarily aimed at securing the well being of the stock but in doing so will strive to improve catches and any associated economic returns to the fisheries: (i) Optimise the number of salmon returning to homewater fisheries. (ii) Maintain and improve the fitness and diversity of salmon stocks. , (iii) Optimise the total economic value of surplus stocks. (iv) Ensure necessary costs are met by beneficiaries. These four objectives will be addressed through local Salmon Action Plans (SAPs) which will be produced for each of the principle salmon rivers in England and Wales by the year 2001. Each plan will review the status of the stock and the fisheries on a particular river, seek to identify the main factors limiting performance, draw up and cost a list of options to address these, and, consult 0with local interest groups. This report is the draft version of the Salmon Action Plan for the River Lune.

Salmon action plan. River Lune - February 1998

In February 1996 A Strategy for the Management of Salmon in England and Wales was launched by the National Rivers Authority. The strategy concentrates on four main objectives for the management of salmon fisheries in England and Wales: (i) Optimise the number of salmon returning to home water fisheries, (ii) Maintain and improve the fitness and diversity of salmon stocks, (iii) Optimise the total economic value of surplus stocks, (iv) Ensure necessary costs are met by beneficiaries. These four objectives will be addressed through local Salmon Action Plans (SAPs) which will be produced for each of the principle salmon rivers in England and Wales by the year 2001. This Salmon Action Plan for the River Lune reviews the status of the stock and the fisheries, seeks to identify the main factors limiting performance, to draw up and cost a list of options to address these, and to consult with local interest groups.

A survey of river habitats on the River Lune

A survey of the River Lune using River Habitat Survey (RHS) was carried out at 103 sections in February/March 99, to which were added 37 sites surveyed between 1994 -1996. Summary statistics were produced on the distribution and extent of flow features (e.g. riffles, pools, rapids etc.), substrate types, tree and associated features and bank profiles. Information on land-use and management was also included in the analyses. A Habitat Modification Score (HMS) describing the level of habitat modification was derived for each site and compared to the whole reference network and to rivers of similar types in Britain. The HMS shows that more than 70% of the sites on the catchment are predominantly unmodified and very few sites are significantly modified. Highly modified sites are concentrated in the urban areas and on the tributaries.

An analysis of the historical catch data from the migratory salmonid fisheries of the River Ribble

The Ribble catchment is the largest and most diverse river system within National Rivers Authority (NRA), North West's Central Area. The river is approximately 100km in length and rises in a limestone area west of the Pennines. This report examines changes in the size and composition of the salmon and sea trout catches from the Ribble migratory salmonid fisheries during the years 1937 to 1991. Comparisons are made between the rod and net fisheries for both salmon and sea trout of the Ribble and Hodder. Patterns of catches shown by the Ribble fisheries are compared with those of other individual rivers and with patterns for the North West Region as a whole. An attempt is made to identify if any relationship exists between catch and stock abundance. Catch patterns shown by the Ribble and Hodder salmon fisheries are compared with electronic resistivity counter data from the two rivers. Annual salmon catch patterns and redd count data are compared both locally and regionally. Recommendations for future studies are made in the light of the report's findings.

An investigation of the recaptures rates for tagged brown trout stocked into the River Ribble

The angling season for non-migratory brown trout, in the Environment Agency (EA) North West Region, runs from March 15th to September 30th. Each year, large numbers of farm reared brown trout are stocked into the rivers of the North West Region's Central Area. In 1994, approximately 20,000 brown trout were introduced into the River systems of the Lune, Wyre and Ribble by local angling clubs and fishery owners. Most of these fish were stocked at a length greater than that defined by local byelaws as the takeable size (200mm). Introductions are made to supplement the existing wild brown trout populations within the river and increase the probability of an angler catching a fish. Stocking with fish of a sufficient length allows the successful angler to remove the catch for their own use. In this way, stretches of the rivers are effectively managed as "put and take" fisheries for brown trout. A number of brown trout fingerlings are also introduced each year by angling clubs and fishery owners. These are stocked with the expectation that the fish will survive in the river to grow, over-winter, and eventually attain a takable size with an increased degree of "wildness". The lower cost of fingerlings, as opposed to trout of a takable length, makes their introduction more attractive to angling clubs since a greater number can be stocked for a given cost. Although the practise of stocking brown trout has occurred for many years in the Central Area, there is little information of its success in terms of increasing anglers catches, or the survival offish introduced. This study was initiated to determine the recapture rates by angling of brown trout following their introduction into a river fishery. The information gained from this study can then be used to give guidance to angling clubs and fishery owners on the optimal strategies for stocking fish.

Geomorphological considerations for the introduction of boulders and groynes for fisheries enhancement: assessment of River Eden at Carhead

This report seeks to briefly provide geomorphological guidance over the introduction of 'habitat enhancement' features for fisheries improvement which is an expanding area of interest throughout the region. This document is a primary attempt to draw together the salient details from the large quantity of literature published in recent years with reference to boulder introduction and to groyne/deflector placement in NW rivers. Secondly the potential introduction of such features is assessed, with reference to the proposed works at Carhead on the Eden.

Salmon action plan: River Kent, July 2001

The report presents the Environment Agency's 5 year Salmon Action Plan for the River Kent for the period from January 2001, providing the background to the plan, responses to the public consultation given, and proposed actions.

Use of biological reference points for the conservation of atlantic salmon (Salmo salar L.)in the River Lune, North West England.

This paper deals with the development and use of biological reference points for salmon conservation on the River Lune, England. The Lune supports recreational and net fisheries with annual catches in the region of 1,000 and 1356 salmon respectively. Using models transported from other river systems, biological reference points exclusive to the Lune were developed; specifically the number of eggs deposited and carrying capacity estimates for age 0+ and 1+ parr. The conservation limit was estimated at 11.9 million eggs and between 1989 and 1998 was exceeded in two years. Comparison of juvenile salmon densities in 1991 and 1997 with estimates of carrying capacity indicated that 0+ and 1+ parr densities were at around 60 % of carrying capacity and may relate to the number of eggs deposited in 1990 and 1996 being approximately 70% of the target value. The paper discusses the management actions taken in order to ensure that the management target of the conservation limit being met four years out of five is delivered. It also discusses the balance between conservation and exploitation and the socio-economic decisions made in order to ensure parity of impacts on the rod and net fisheries. The regulations have been enforced since 1999 and the paper concludes with an assessment of the actions taken to deliver the management targets, over the last five years.